Problem:


Score : 600 points

Problem Statement

There is a tree with N vertices numbered 1 to N.
The i-th edge in this tree connects Vertex a_i and Vertex b_i, and the color and length of that edge are c_i and d_i, respectively.
Here the color of each edge is represented by an integer between 1 and N-1 (inclusive). The same integer corresponds to the same color, and different integers correspond to different colors.

Answer the following Q queries:

Query j (1 \leq j \leq Q): assuming that the length of every edge whose color is x_j is changed to y_j, find the distance between Vertex u_j and Vertex v_j. (The changes of the lengths of edges do not affect the subsequent queries.)

Constraints

2 \leq N \leq 10^5

1 \leq Q \leq 10^5

1 \leq a_i, b_i \leq N

1 \leq c_i \leq N-1

1 \leq d_i \leq 10^4

1 \leq x_j \leq N-1

1 \leq y_j \leq 10^4

1 \leq u_j < v_j \leq N

The given graph is a tree.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N Q
a_1 b_1 c_1 d_1
:
a_{N-1} b_{N-1} c_{N-1} d_{N-1}
x_1 y_1 u_1 v_1
:
x_Q y_Q u_Q v_Q

Output

Print Q lines. The j-th line (1 \leq j \leq Q) should contain the answer to Query j.

Sample Input 1

5 3
1 2 1 10
1 3 2 20
2 4 4 30
5 2 1 40
1 100 1 4
1 100 1 5
3 1000 3 4

Sample Output 1

130
200
60

The graph in this input is as follows:

Here the edges of Color 1 are shown as solid red lines, the edge of Color 2 is shown as a bold green line, and the edge of Color 4 is shown as a blue dashed line.

Query 1: Assuming that the length of every edge whose color is 1 is changed to 100, the distance between Vertex 1 and Vertex 4 is 100 + 30 = 130.

Query 2: Assuming that the length of every edge whose color is 1 is changed to 100, the distance between Vertex 1 and Vertex 5 is 100 + 100 = 200.

Query 3: Assuming that the length of every edge whose color is 3 is changed to 1000 (there is no such edge), the distance between Vertex 3 and Vertex 4 is 20 + 10 + 30 = 60. Note that the edges of Color 1 now have their original lengths.



Sample input:
5 3
1 2 1 10
1 3 2 20
2 4 4 30
5 2 1 40
1 100 1 4
1 100 1 5
3 1000 3 4


Sample output:
130
200
60

Submission status: Runtime Error

Solution code:
import sys
from itertools import combinations, permutations, product, combinations_with_replacement, accumulate
from heapq import heapify, heappop, heappush, heappushpop
from bisect import bisect_left, bisect_right
from collections import Counter, defaultdict, deque
from math import sqrt, log, floor, ceil, factorial, cos, sin, pi  # , gcd
from fractions import gcd
from operator import mul
from functools import reduce

sys.setrecursionlimit(10 ** 8)
input = sys.stdin.readline
INF = float('inf')
LINF = 2 ** 63 - 1
NIL = -LINF
MOD = 10 ** 9 + 7
MGN = 4


def AST(exp: bool, msg: str = ""): assert exp, msg


def TAST(exp: bool, msg=""):
    if exp is False: print("TAssertionError:", msg)
    while exp is False:
        pass


def EPR(msg): print(msg, file=sys.stderr)


def II(): return int(input())


def IF(): return float(input())


def IS(): return input().replace('\n', '')


def ILCI(n: int): return [II() for _ in range(n)]


def ILCF(n: int): return [IF() for _ in range(n)]


def ILI(): return list(map(int, input().split()))


def ILLI(n: int): return [[int(j) for j in input().split()] for i in range(n)]


def ILF(): return list(map(float, input().split()))


def ILLF(n: int): return [[float(j) for j in input().split()] for i in range(n)]


def LTOS(lst: list, sep: str = ' '): return sep.join(map(str, lst))


def DEC(lst: list): return list(map(lambda x: x - 1, lst))


def INC(lst: list): return list(map(lambda x: x + 1, lst))


class Queue:
    def __init__(self) -> None:
        self.items = deque()

    def is_empty(self) -> bool:
        return len(self.items) == 0

    def enqueue(self, item) -> None:
        self.items.appendleft(item)

    def insert(self, item) -> None:
        self.enqueue(item)

    def dequeue(self):
        return self.items.pop()

    def front(self):
        return self.items[-1]

    def pop(self) -> None:
        self.items.pop()

    def size(self) -> int:
        return len(self.items)


class LCA:
    def __init__(self, N: int) -> None:
        self.N = N
        self.to = [[] for _ in range(N)]
        self.co = [[] for _ in range(N)]
        self.dep = [0] * N
        self.costs = [0] * N
        l = 0
        while (1 << l) < N:
            l += 1
        self.l = l
        self.par = [([0] * l) for _ in range(N + 1)]

    def add_edge(self, a: int, b: int, c=0) -> None:
        self.to[a].append(b)
        self.co[a].append(c)
        self.to[b].append(a)
        self.co[b].append(c)

    '''
    def _dfs(self, v: int, d: int = 0, c = 0, p: int = -1) -> None:
        if p != -1:
            self.par[v][0] = p
        self.dep[v] = d
        self.costs[v] = c
        for i in range(len(self.to[v])):
            u = self.to[v][i]
            if u == p:
                continue
            else:
                self._dfs(u, d+1, c+self.co[v][i], v)
    '''

    def _bfs(self, root: int) -> None:
        que = Queue()
        que.enqueue(root)
        self.dep[root] = 0
        self.costs[root] = 0
        vis = [False] * self.N
        while que.is_empty() is False:
            v = que.dequeue()
            vis[v] = True
            nd = self.dep[v] + 1
            cs = self.costs[v]
            for i in range(len(self.to[v])):
                nv = self.to[v][i]
                if vis[nv]:
                    continue
                else:
                    que.enqueue(nv)
                    self.dep[nv] = nd
                    self.costs[nv] = cs + self.co[v][i]
                    self.par[nv][0] = v

    def init(self, root: int = 0) -> None:
        self.root = root
        self._bfs(root)
        for i in range(self.l - 1):
            for v in range(self.N):
                self.par[v][i + 1] = self.par[self.par[v][i]][i]

    def lca(self, a: int, b: int) -> int:
        dep_s, dep_l = self.dep[a], self.dep[b]
        if dep_s > dep_l:
            a, b = b, a
            dep_s, dep_l = dep_l, dep_s
        gap = dep_l - dep_s
        L_1 = self.l - 1
        par = self.par
        for i in range(L_1, -1, -1):
            leng = 1 << i
            if gap >= leng:
                gap -= leng
                b = par[b][i]
        if a == b:
            return a
        for i in range(L_1, -1, -1):
            na = par[a][i]
            nb = par[b][i]
            if na != nb:
                a, b = na, nb
        return par[a][0]

    def length(self, a: int, b: int) -> int:
        c = self.lca(a, b)
        dep = self.dep
        return dep[a] + dep[b] - dep[c] * 2

    def dist(self, a: int, b: int):
        c = self.lca(a, b)
        costs = self.costs
        return costs[a] + costs[b] - costs[c] * 2


def main():
    N, Q = ILI()
    gr = LCA(N)
    es = [[] for _ in range(N)]
    for i in range(N - 1):
        a, b, col, dist = ILI()
        a -= 1;
        b -= 1
        es[a].append((b, dist, col))
        es[b].append((a, dist, col))
        gr.add_edge(a, b, dist)

    gr.init()
    ans = [0] * Q
    qs = [[] for _ in range(N)]
    for i in range(Q):
        cx, dy, a, b = ILI()
        a -= 1;
        b -= 1
        # ans[i] = gr.dist(a, b)
        c = gr.lca(a, b)
        ans[i] = gr.costs[a] + gr.costs[b] - gr.costs[c] * 2
        qs[a].append((cx, i, 1, dy))
        qs[b].append((cx, i, 1, dy))
        qs[c].append((cx, i, -2, dy))

    cnt = [0] * N
    sum_ = [0] * N

    '''
    def dfs(v: int, p: int = -1) -> None:
        for (col, qid, coeff, dist) in qs[v]:
            x = -sum_[col]
            x += dist * cnt[col]
            ans[qid] += x * coeff

        for (to, co, col) in es[v]:
            if to == p:
                continue
            cnt[col] += 1
            sum_[col] += co

            dfs(to, v)

            cnt[col] -= 1
            sum_[col] -= co
    '''

    sk = []
    tr = [{} for _ in range(N)]
    vis = [False] * N

    def dfs2(v: int, p: int = -1) -> None:
        for (col, qid, coeff, dist) in qs[v]:
            x = -sum_[col]
            x += dist * cnt[col]
            ans[qid] += x * coeff

        vis[v] = True

        for (to, co, col) in reversed(es[v]):
            if to == p:
                continue
            sk.append((to, v, col, co))
            tr[v][to] = (col, co)

        while len(sk) > 0:
            v, p, cl, cs = sk[-1]
            if len(es[v]) == 1:
                sk.pop()

            if vis[v] and p >= 0:
                cl, cs = tr[p][v]
                cnt[cl] -= 1
                sum_[cl] -= cs
                tr[p].pop(v)
                sk.pop()
                continue

            cnt[cl] += 1
            sum_[cl] += cs

            for (col, qid, coeff, dist) in qs[v]:
                x = -sum_[col]
                x += dist * cnt[col]
                ans[qid] += x * coeff

            vis[v] = True

            for (to, co, col) in reversed(es[v]):
                if to == p:
                    continue
                sk.append((to, v, col, co))
                tr[v][to] = (col, co)

            if len(tr[v]) <= 1:
                cl, cs = tr[p][v]
                cnt[cl] -= 1
                sum_[cl] -= cs
                tr[p].pop(v)

    dfs2(0)

    print(*ans, sep='\n')


if __name__ == '__main__':
    main()

Submission status: Runtime Error

Solution code:
import sys
from itertools import combinations, permutations, product, combinations_with_replacement, accumulate
from heapq import heapify, heappop, heappush, heappushpop
from bisect import bisect_left, bisect_right
from collections import Counter, defaultdict, deque
from math import sqrt, log, floor, ceil, factorial, cos, sin, pi#, gcd
from fractions import gcd
from operator import mul
from functools import reduce
sys.setrecursionlimit(10**8)
input = sys.stdin.readline
INF = float('inf')
LINF = 2**63-1
NIL = -LINF
MOD = 10**9+7
MGN = 4
def AST(exp: bool, msg: str = ""): assert exp, msg
def TAST(exp: bool, msg = ""):
    if exp is False: print("TAssertionError:", msg)
    while exp is False:
        pass
def EPR(msg): print(msg, file=sys.stderr)
def II(): return int(input())
def IF(): return float(input())
def IS(): return input().replace('\n', '')
def ILCI(n: int): return [II() for _ in range(n)]
def ILCF(n: int): return [IF() for _ in range(n)]
def ILI(): return list(map(int, input().split()))
def ILLI(n: int): return [[int(j) for j in input().split()] for i in range(n)]
def ILF(): return list(map(float, input().split()))
def ILLF(n: int): return [[float(j) for j in input().split()] for i in range(n)]
def LTOS(lst: list, sep: str = ' '): return sep.join(map(str, lst))
def DEC(lst: list): return list(map(lambda x: x-1, lst))
def INC(lst: list): return list(map(lambda x: x+1, lst))

class LCA:
    def __init__(self, N: int) -> None:
        self.N = N
        self.to = [[] for _ in range(N)]  
        self.co = [[] for _ in range(N)]  
        self.dep = [0] * N  
        self.costs = [0] * N  
        l = 0
        while (1 << l) < N:
            l += 1
        self.l = l
        self.par = [([0]*l) for _ in range(N+1)]  
    def add_edge(self, a: int, b: int, c = 0) -> None:
        self.to[a].append(b)
        self.co[a].append(c)
        self.to[b].append(a)
        self.co[b].append(c)
    def _dfs(self, v: int, d: int = 0, c = 0, p: int = -1) -> None:
        if p != -1:
            self.par[v][0] = p  
        self.dep[v] = d
        self.costs[v] = c
        for i in range(len(self.to[v])):
            u = self.to[v][i]
            if u == p:
                continue
            else:
                self._dfs(u, d+1, c+self.co[v][i], v)
    def init(self, root: int = 0) -> None:
        self.root = root
        self._dfs(root)
        for i in range(self.l - 1):
            for v in range(self.N):
                self.par[v][i+1] = self.par[self.par[v][i]][i]
    def __call__(self, a: int, b: int) -> int:
        dep_s, dep_l = self.dep[a], self.dep[b]
        self_par = self.par
        if dep_s > dep_l:
            a, b = b, a  
            dep_s, dep_l = dep_l, dep_s
        gap = dep_l - dep_s
        L_1 = self.l-1
        for i in range(L_1, -1, -1):
            leng = 1 << i
            if gap >= leng:
                gap -= leng
                b = self_par[b][i]
        if a == b:  
            return a
        for i in range(L_1, -1, -1):
            na = self_par[a][i]
            nb = self_par[b][i]
            if na != nb:
                a, b = na, nb
        return self_par[a][0]
    def length(self, a: int, b: int) -> int:
        c = self.__call__(a, b)
        return self.dep[a] + self.dep[b] - self.dep[c] * 2
    def dist(self, a: int, b: int):
        c = self.__call__(a, b)
        return self.costs[a] + self.costs[b] - self.costs[c] * 2

def main():
    N,Q = ILI()
    gr = LCA(N)
    es = [[] for _ in range(N)]
    for i in range(N-1):
        a,b, col, dist = ILI()
        a -= 1; b -= 1
        es[a].append((b, dist, col))
        es[b].append((a, dist, col))
        gr.add_edge(a, b, dist)

    gr.init()
    ans = [0] * Q
    qs = [[] for _ in range(N)]
    for i in range(Q):
        cx,dy, a,b = ILI()
        a -= 1; b -= 1
        #c = gr(a, b)
        ans[i] = gr.costs[a] + gr.costs[b] - gr.costs[c] * 2
        qs[a].append((cx, i, 1, dy))
        qs[b].append((cx, i, 1, dy))
        qs[c].append((cx, i, -2, dy))

    cnt = [0] * N
    sum_ = [0] * N

    def dfs(v: int, p: int = -1) -> None:
        for (col,qid,coeff,dist) in qs[v]:
            x = -sum_[col]
            x += dist * cnt[col]
            ans[qid] += x * coeff
        
        for (to, co, col) in es[v]:
            if to == p:
                continue
            cnt[col] += 1
            sum_[col] += co
            dfs(to, v)
            cnt[col] -= 1
            sum_[col] -= co

    dfs(0)

    for an in ans:
        print(an)


if __name__ == '__main__':
    main()

Submission status: Runtime Error

Solution code:
import numpy as np
import sys
from itertools import combinations, permutations, product, combinations_with_replacement, accumulate
from heapq import heapify, heappop, heappush, heappushpop
from bisect import bisect_left, bisect_right
from collections import Counter, defaultdict, deque
from math import sqrt, log, floor, ceil, factorial, cos, sin, pi#, gcd
from fractions import gcd
from operator import mul
from functools import reduce
sys.setrecursionlimit(10**8)
input = sys.stdin.readline
INF = float('inf')
LINF = 2**63-1
NIL = -LINF
MOD = 10**9+7
MGN = 4
def AST(exp: bool, msg: str = ""): assert exp, msg
def TAST(exp: bool, msg = ""):
    if exp is False: print("TAssertionError:", msg)
    while exp is False:
        pass
def EPR(msg): print(msg, file=sys.stderr)
def II(): return int(input())
def IF(): return float(input())
def IS(): return input().replace('\n', '')
def ILCI(n: int): return [II() for _ in range(n)]
def ILCF(n: int): return [IF() for _ in range(n)]
def ILI(): return list(map(int, input().split()))
def ILLI(n: int): return [[int(j) for j in input().split()] for i in range(n)]
def ILF(): return list(map(float, input().split()))
def ILLF(n: int): return [[float(j) for j in input().split()] for i in range(n)]
def LTOS(lst: list, sep: str = ' '): return sep.join(map(str, lst))
def DEC(lst: list): return list(map(lambda x: x-1, lst))
def INC(lst: list): return list(map(lambda x: x+1, lst))

class LCA:
    def __init__(self, N: int) -> None:
        self.N = N
        self.to = [[] for _ in range(N)]  
        self.co = [[] for _ in range(N)]  
        self.dep = [0] * N  
        self.costs = [0] * N  
        l = 0
        while (1 << l) < N:
            l += 1
        self.l = l
        #self.par = [([0]*l) for _ in range(N+1)]
        #self.par = np.array([([0]*l) for _ in range(N+1)])
        self.par = np.zeros((N+1, l), dtype=np.int64)
    def add_edge(self, a: int, b: int, c = 0) -> None:
        self.to[a].append(b)
        self.co[a].append(c)
        self.to[b].append(a)
        self.co[b].append(c)
    def _dfs(self, v: int, d: int = 0, c = 0, p: int = -1) -> None:
        if p != -1:
            self.par[v][0] = p
        self.dep[v] = d
        self.costs[v] = c
        for i in range(len(self.to[v])):
            u = self.to[v][i]
            if u == p:
                continue
            else:
                self._dfs(u, d+1, c+self.co[v][i], v)
    def init(self, root: int = 0) -> None:
        self.root = root
        self._dfs(root)
        for i in range(self.l - 1):
            for v in range(self.N):
                self.par[v][i+1] = self.par[self.par[v][i]][i]
    def __call__(self, a: int, b: int) -> int:
        dep_s, dep_l = self.dep[a], self.dep[b]
        if dep_s > dep_l:
            a, b = b, a  
            dep_s, dep_l = dep_l, dep_s
        gap = dep_l - dep_s
        L_1 = self.l-1
        for i in range(L_1, -1, -1):
            leng = 1 << i
            if gap >= leng:
                gap -= leng
                #b = self.par[b][i]
                b = self.par[b, i]
        if a == b:  
            return a
        for i in range(L_1, -1, -1):
            #na = self.par[a][i]
            #nb = self.par[b][i] 
            na = self.par[a, i]
            nb = self.par[b, i] 
            if na != nb:
                a, b = na, nb
        return self.par[a, 0]
    def length(self, a: int, b: int) -> int:
        c = self.__call__(a, b)
        return self.dep[a] + self.dep[b] - self.dep[c] * 2
    def dist(self, a: int, b: int):
        c = self.__call__(a, b)
        return self.costs[a] + self.costs[b] - self.costs[c] * 2

def main():
    N,Q = ILI()
    gr = LCA(N)
    es = [[] for _ in range(N)]
    for i in range(N-1):
        a,b, col, dist = ILI()
        a -= 1; b -= 1
        es[a].append((b, dist, col))
        es[b].append((a, dist, col))
        gr.add_edge(a, b, dist)

    gr.init()
    ans = [0] * Q
    qs = [[] for _ in range(N)]
    for i in range(Q):
        cx,dy, a,b = ILI()
        a -= 1; b -= 1
        c = gr(a, b)
        ans[i] = gr.costs[a] + gr.costs[b] - gr.costs[c] * 2
        qs[a].append((cx, i, 1, dy))
        qs[b].append((cx, i, 1, dy))
        qs[c].append((cx, i, -2, dy))

    cnt = [0] * N
    sum_ = [0] * N

    def dfs(v: int, p: int = -1) -> None:
        for (col,qid,coeff,dist) in qs[v]:
            x = -sum_[col]
            x += dist * cnt[col]
            ans[qid] += x * coeff
        
        for (to, co, col) in es[v]:
            if to == p:
                continue
            cnt[col] += 1
            sum_[col] += co
            dfs(to, v)
            cnt[col] -= 1
            sum_[col] -= co

    dfs(0)
    for i in range(Q):
        print(ans[i])


if __name__ == '__main__':
    main()

Submission status: Runtime Error

Solution code:
import sys
from itertools import combinations, permutations, product, combinations_with_replacement, accumulate
from heapq import heapify, heappop, heappush, heappushpop
from bisect import bisect_left, bisect_right
from collections import Counter, defaultdict, deque
from math import sqrt, log, floor, ceil, factorial, cos, sin, pi#, gcd
from fractions import gcd
from operator import mul
from functools import reduce
sys.setrecursionlimit(10**5)
input = sys.stdin.readline
INF = float('inf')
LINF = 2**63-1
NIL = -LINF
MOD = 10**9+7
MGN = 4
def AST(exp: bool, msg: str = ""): assert exp, msg
def TAST(exp: bool, msg = ""):
    if exp is False: print("TAssertionError:", msg)
    while exp is False:
        pass
def II(): return int(input())
def IF(): return float(input())
def IS(): return input().replace('\n', '')
def ILCI(n: int): return [II() for _ in range(n)]
def ILCF(n: int): return [IF() for _ in range(n)]
def ILI(): return list(map(int, input().split()))
def ILLI(n: int): return [[int(j) for j in input().split()] for i in range(n)]
def ILF(): return list(map(float, input().split()))
def ILLF(n: int): return [[float(j) for j in input().split()] for i in range(n)]
def LTOS(lst: list, sep: str = ' '): return sep.join(map(str, lst))
def DEC(lst: list): return list(map(lambda x: x-1, lst))
def INC(lst: list): return list(map(lambda x: x+1, lst))

class LCA:
    def __init__(self, N: int) -> None:
        self.N = N
        self.to = [[] for _ in range(N)]  
        self.co = [[] for _ in range(N)]  
        self.dep = [0]*N  
        self.costs = [None] * N  
        l = 0
        while (1 << l) < N:
            l += 1
        self.l = l
        self.par = [([l]*N) for _ in range(N+1)]  
    def add_edge(self, a: int, b: int, c = 0) -> None:
        self.to[a].append(b)
        self.co[a].append(c)
        self.to[b].append(a)
        self.co[b].append(c)
    def _dfs(self, v: int, d: int = 0, c = 0, p: int = -1) -> None:
        if p != -1:
            self.par[v][0] = p  
        self.dep[v] = d
        self.costs[v] = c
        for i in range(len(self.to[v])):
            u = self.to[v][i]
            if u == p:
                continue
            else:
                self._dfs(u, d+1, c+self.co[v][i], v)
    def init(self, root: int = 0) -> None:
        self.root = root
        self._dfs(root)
        for i in range(self.l - 1):
            for v in range(self.N):
                self.par[v][i+1] = self.par[self.par[v][i]][i]
    def __call__(self, a: int, b: int) -> int:
        if self.dep[a] > self.dep[b]:  
            a, b = b, a  
        gap = self.dep[b] - self.dep[a]
        for i in range(self.l-1, -1, -1):
            leng = 1 << i
            if gap >= leng:
                gap -= leng
                b = self.par[b][i]
        if a == b:  
            return a
        for i in range(self.l-1, -1, -1):
            na = self.par[a][i]  
            nb = self.par[b][i]  
            if na != nb:
                a, b = na, nb
        return self.par[a][0]
    def length(self, a: int, b: int) -> int:
        c = self.__call__(a, b)
        return self.dep[a] + self.dep[b] - self.dep[c] * 2
    def dist(self, a: int, b: int):
        c = self.__call__(a, b)
        return self.costs[a] + self.costs[b] - self.costs[c] * 2

def main():
    N,Q = ILI()
    gr = LCA(N)
    es = [[] for _ in range(N)]
    for i in range(N-1):
        a,b, col, dist = ILI()
        a -= 1; b -= 1
        es[a].append((b, dist, col))
        es[b].append((a, dist, col))
        gr.add_edge(a, b, dist)

    gr.init()
    ans = [0] * Q
    qs = [[] for _ in range(N)]
    for i in range(Q):
        cx,dy, a,b = ILI()
        a -= 1; b -= 1
        c = gr(a, b)
        ans[i] = gr.costs[a] + gr.costs[b] - gr.costs[c] * 2
        qs[a].append((cx, i, 1, dy))
        qs[b].append((cx, i, 1, dy))
        qs[c].append((cx, i, -2, dy))

    cnt = [0] * N
    sum_ = [0] * N

    def dfs(v: int, p: int = -1) -> None:
        for q in qs[v]:
            col,qid,coeff,dist = q
            x = -sum_[col]
            x += dist * cnt[col]
            ans[qid] += x * coeff
        
        for e in es[v]:
            (to, co, col) = e
            if to == p:
                continue
            cnt[col] += 1
            sum_[col] += co
            dfs(to, v)
            cnt[col] -= 1
            sum_[col] -= co

    dfs(0)
    for i in range(Q):
        print(ans[i])


if __name__ == '__main__':
    main()

Submission status: Runtime Error

Solution code:
import sys
from itertools import combinations, permutations, product, combinations_with_replacement, accumulate
from heapq import heapify, heappop, heappush, heappushpop
from bisect import bisect_left, bisect_right
from collections import Counter, defaultdict, deque
from math import sqrt, log, floor, ceil, factorial, cos, sin, pi#, gcd
from fractions import gcd
from operator import mul
from functools import reduce
sys.setrecursionlimit(10**5)
input = sys.stdin.readline
INF = float('inf')
LINF = 2**63-1
NIL = -LINF
MOD = 10**9+7
MGN = 4
def AST(exp: bool, msg: str = ""): assert exp, msg
def TAST(exp: bool, msg = ""):
    if exp is False: print("TAssertionError:", msg)
    while exp is False:
        pass
def II(): return int(input())
def IF(): return float(input())
def IS(): return input().replace('\n', '')
def ILCI(n: int): return [II() for _ in range(n)]
def ILCF(n: int): return [IF() for _ in range(n)]
def ILI(): return list(map(int, input().split()))
def ILLI(n: int): return [[int(j) for j in input().split()] for i in range(n)]
def ILF(): return list(map(float, input().split()))
def ILLF(n: int): return [[float(j) for j in input().split()] for i in range(n)]
def LTOS(lst: list, sep: str = ' '): return sep.join(map(str, lst))
def DEC(lst: list): return list(map(lambda x: x-1, lst))
def INC(lst: list): return list(map(lambda x: x+1, lst))

class LCA:
    def __init__(self, N: int) -> None:
        self.N = N
        self.to = [[] for _ in range(N)]  
        self.co = [[] for _ in range(N)]  
        self.dep = [0]*N  
        self.costs = [None] * N  
        l = 0
        while (1 << l) < N:
            l += 1
        self.l = l
        self.par = [([l]*N) for _ in range(N+1)]  
    def add_edge(self, a: int, b: int, c = 0) -> None:
        self.to[a].append(b)
        self.co[a].append(c)
        self.to[b].append(a)
        self.co[b].append(c)
    def _dfs(self, v: int, d: int = 0, c = 0, p: int = -1) -> None:
        if p != -1:
            self.par[v][0] = p  
        self.dep[v] = d
        self.costs[v] = c
        for i in range(len(self.to[v])):
            u = self.to[v][i]
            if u == p:
                continue
            else:
                self._dfs(u, d+1, c+self.co[v][i], v)
    def init(self, root: int = 0) -> None:
        self.root = root
        self._dfs(root)
        for i in range(self.l - 1):
            for v in range(self.N):
                self.par[v][i+1] = self.par[self.par[v][i]][i]
    def __call__(self, a: int, b: int) -> int:
        if self.dep[a] > self.dep[b]:  
            a, b = b, a  
        gap = self.dep[b] - self.dep[a]
        for i in range(self.l-1, -1, -1):
            leng = 1 << i
            if gap >= leng:
                gap -= leng
                b = self.par[b][i]
        if a == b:  
            return a
        for i in range(self.l-1, -1, -1):
            na = self.par[a][i]  
            nb = self.par[b][i]  
            if na != nb:
                a, b = na, nb
        return self.par[a][0]
    def length(self, a: int, b: int) -> int:
        c = self.__call__(a, b)
        return self.dep[a] + self.dep[b] - self.dep[c] * 2
    def dist(self, a: int, b: int):
        c = self.__call__(a, b)
        return self.costs[a] + self.costs[b] - self.costs[c] * 2

def main():
    N,Q = ILI()
    gr = LCA(N)
    es = [[] for _ in range(N)]
    for i in range(N-1):
        a,b, col, dist = ILI()
        a -= 1
        b -= 1
        es[a].append((b, dist, col))
        es[b].append((a, dist, col))
        gr.add_edge(a, b, dist)

    gr.init()
    ans = [0] * Q
    qs = [[] for _ in range(N)]
    for i in range(Q):
        cx,dy, a,b = ILI()
        a -= 1
        b -= 1
        c = gr(a, b)
        ans[i] = gr.costs[a] + gr.costs[b] - gr.costs[c] * 2
        qs[a].append((cx, i, 1, dy))
        qs[b].append((cx, i, 1, dy))
        qs[c].append((cx, i, -2, dy))

    cnt = [0] * N
    sum = [0] * N

    def dfs(v: int, p: int = -1) -> None:
        for q in qs[v]:
            col,qid,coeff,dist = q
            x = -sum[col]
            x += dist * cnt[col]
            ans[qid] += x * coeff
        
        for e in es[v]:
            (to, co, col) = e
            if to == p:
                continue
            cnt[col] += 1
            sum[col] += co
            dfs(to, v)
            cnt[col] -= 1
            sum[col] -= co

    dfs(0)
    for i in range(Q):
        print(ans[i])


if __name__ == '__main__':
    main()

Submission status: Runtime Error

Solution code:
class LCA(object):
    def __init__(self, to, root=0):
        self.__n = len(to)
        self.__to = to
        self.__logn = (self.__n-1).bit_length()
        self.__depth = [-1]*self.__n
        self.__dist = [-1]*self.__n
        self.__depth[root] = 0
        self.__dist[root] = 0
        self.__parents = [[-1]*self.__n for _ in range(self.__logn)]
        self.__dfs(root)
        self.__doubling()

    def __dfs(self, v):
        for u, c, d in self.__to[v]:
            if self.__depth[u] != -1:
                continue
            self.__parents[0][u] = v
            self.__depth[u] = self.__depth[v]+1
            self.__dist[u] = self.__dist[v]+d
            self.__dfs(u)

    def __doubling(self):
        for i in range(1, self.__logn):
            for v in range(self.__n):
                if self.__parents[i-1][v] == -1:
                    continue
                self.__parents[i][v] = \
                    self.__parents[i-1][self.__parents[i-1][v]]

    @property
    def depth(self):
        return self.__depth

    @property
    def dist(self):
        return self.__dist

    def get(self, u, v):
        dd = self.__depth[v] - self.__depth[u]
        if dd < 0:
            u, v = v, u
            dd *= -1
        for i in range(self.__logn):
            if dd & (2**y):
                v = self.__parents[i][v]
        if v == u: return v
        for i in range(self.__logn-1, -1, -1):
            pu = self.__parents[i][u]
            pv = self.__parents[i][v]
            if pu != pv: u, v = pu, pv
        return self.__parents[0][u]
  
n, q = map(int, input().split())
to = [list() for _ in range(n)]
for _ in range(n-1):
    a, b, c, d = map(int, input().split())
    a -= 1
    b -= 1
    to[a].append((b, c, d))
    to[b].append((a, c, d))

G = LCA(to)

Query = [list() for _ in range(n)]
for i in range(q):
    #idx, color, mag, coef
    x, y, u, v = map(int, input().split())
    u -= 1
    v -= 1
    c = G.get(u, v)
    Query[u].append((i, x, y, 1))
    Query[v].append((i, x, y, 1))
    Query[c].append((i, x, y, -2))

ans = [0]*q
S = [[0, 0] for _ in range(n)]

def dfs(v, p=-1):
    for idx, color, mag, coef in Query[v]:
        x = G.dist[v]
        x -= S[color][1]
        x += mag*S[color][0]
        ans[idx] += x*coef
    for nv, color, d in to[v]:
        if nv == p: continue
        S[color][0] += 1
        S[color][1] += d
        dfs(nv, v)
        S[color][0] -= 1
        S[color][1] -= d
    return ans

print(*dfs(0), sep="\n")