Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline

n,m = map(int, input().split())
t = sorted([tuple(map(int, input().split())) for i in range(m)])
INF = 10 ** 18
dp = [0] + [INF] * (n-1) # 頂点1から、各頂点(1~n)までの最短距離
for l,r,c in t:
  for i in range(r,l,-1):
    if dp[l] + c < dp[i]:
      dp[i] = dp[l] + c
    else:
      break
ans = dp[n-1]
if ans == INF:
  print(-1)
else:
  print(ans)


Fixed submission:
import sys
input = sys.stdin.readline

import heapq
N,M = map(int,input().split())
LRC = [tuple(map(int,input().split())) for i in range(M)]

es = [[] for i in range(N)]
for l,r,c in LRC:
    l,r = l-1,r-1
    es[l].append((r,c))
for i in range(N-1):
    es[i+1].append((i,0))

INF = 10 ** 18
dist = [INF]*N
dist[0] = 0
hq = [(0,0)]
heapq.heapify(hq)

while(hq):
    d,v = heapq.heappop(hq)
    if v==N-1:
        print(d)
        exit()
    for to,c in es[v]:
        if d+c >= dist[to]: continue
        dist[to] = d+c
        heapq.heappush(hq, (d+c, to))
print(-1)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline

n,m = map(int, input().split())
t = sorted([tuple(map(int, input().split())) for i in range(m)])
d=[0,0]+[1e18]*n
for l,r,c in t:
  for i in range(r,l,-1):
    if d[l]+c<d[i]:
      d[i]=d[l]+c
    else:
      break
print(d[-2]%10**18or-1)

Fixed submission:
import sys
input = sys.stdin.readline

import heapq
N,M = map(int,input().split())
LRC = [tuple(map(int,input().split())) for i in range(M)]

es = [[] for i in range(N)]
for l,r,c in LRC:
    l,r = l-1,r-1
    es[l].append((r,c))
for i in range(N-1):
    es[i+1].append((i,0))

INF = 10 ** 18
dist = [INF]*N
dist[0] = 0
hq = [(0,0)]
heapq.heapify(hq)

while(hq):
    d,v = heapq.heappop(hq)
    if v==N-1:
        print(d)
        exit()
    for to,c in es[v]:
        if d+c >= dist[to]: continue
        dist[to] = d+c
        heapq.heappush(hq, (d+c, to))
print(-1)

Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline

class RangeUpdateQuery:
    def __init__(self, n):
        self.n0 = 2**(n-1).bit_length()
        self.INF = 10 ** 18
        self.data = [self.INF]*(2*self.n0-1)

    def update(self, l,r,v):
        l += self.n0
        r += self.n0
        while l < r:
            if r&1:
                r -= 1
                if self.data[r-1] > v:
                    self.data[r-1] = v
            if l&1:
                if self.data[l-1] > v:
                    self.data[l-1] = v
                l += 1
            l >>=1
            r >>=1

    def query(self, i):
        i += self.n0-1
        res = self.INF
        while i+1:
            if self.data[i] < res:
                res = self.data[i]
            i = ~-i//2
        return res

n,m = map(int, input().split())
light = [list(map(int, input().split())) for i in range(m)]
light.sort()
RUQ = RangeUpdateQuery(n-1)
RUQ.update(0,1,0)
for a,b,c in light:
    cur = RUQ.query(a-1)
    RUQ.update(a, b, cur+c)

ans = RUQ.query(n-1)
if ans >= 10 ** 18:
  print(-1)
else:
  print(ans)


Fixed submission:
import sys
input = sys.stdin.readline

import heapq
N,M = map(int,input().split())
LRC = [tuple(map(int,input().split())) for i in range(M)]

es = [[] for i in range(N)]
for l,r,c in LRC:
    l,r = l-1,r-1
    es[l].append((r,c))
for i in range(N-1):
    es[i+1].append((i,0))

INF = 10 ** 18
dist = [INF]*N
dist[0] = 0
hq = [(0,0)]
heapq.heapify(hq)

while(hq):
    d,v = heapq.heappop(hq)
    if v==N-1:
        print(d)
        exit()
    for to,c in es[v]:
        if d+c >= dist[to]: continue
        dist[to] = d+c
        heapq.heappush(hq, (d+c, to))
print(-1)

Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline

class RangeUpdateQuery:
    def __init__(self, n):
        self.n0 = 2**(n-1).bit_length()
        self.INF = 10 ** 18
        self.data = [self.INF]*(2*self.n0-1)

    def update(self, l,r,v):
        l += self.n0
        r += self.n0
        while l < r:
            if r&1:
                r -= 1
                if self.data[r-1] > v:
                    self.data[r-1] = v
            if l&1:
                if self.data[l-1] > v:
                    self.data[l-1] = v
                l += 1
            l >>=1
            r >>=1

    def query(self, i):
        i += self.n0-1
        res = self.INF
        while i+1:
            if self.data[i] < res:
                res = self.data[i]
            i = ~-i//2
        return res

n,m = map(int, input().split())
light = [list(map(int, input().split())) for i in range(m)]
light.sort()
RUQ = RangeUpdateQuery(n-1)
RUQ.update(0,1,0)
for a,b,c in light:
    cur = RUQ.query(a-1)
    RUQ.update(a, b, cur+c)

ans = RUQ.query(n-1)
if ans >= 10 ** 18:
  print(-1)
else:
  print(ans)


Fixed submission:
import sys
input = sys.stdin.readline

import heapq
N,M = map(int,input().split())
LRC = [tuple(map(int,input().split())) for i in range(M)]

es = [[] for i in range(N)]
for l,r,c in LRC:
    l,r = l-1,r-1
    es[l].append((r,c))
for i in range(N-1):
    es[i+1].append((i,0))

INF = 10 ** 18
dist = [INF]*N
dist[0] = 0
hq = [(0,0)]
heapq.heapify(hq)

while(hq):
    d,v = heapq.heappop(hq)
    if v==N-1:
        print(d)
        exit()
    for to,c in es[v]:
        if d+c >= dist[to]: continue
        dist[to] = d+c
        heapq.heappush(hq, (d+c, to))
print(-1)