Problem p02599 (python)

Fixed submission:
import sys
input = sys.stdin.readline
class BIT:
    """
    Binary Index Tree
    ###1-origin####

    add :L[i]+=x
    sum: sum(L[:l])
    range_sum : sum(L[l:r])

    #material http://hos.ac/slides/20140319_bit.pdf
    """

    def __init__(self, N, init_val=0):
        self.init_val = init_val
        self.size = N
        self.L = [init_val]*(N+1)

    def sum(self, r):
        """
        sum[,r)
        calc sum from L[0] to L[r-1]
        """
        ret = self.init_val
        while r > 0:
            ret += self.L[r]
            r -= r & (-r)

        return ret

    def range_sum(self, l, r):
        
        """
        idx周りが怪しい?
        sum[l,r)
        calc sum from L[l] to L[r-1]
        """
        return self.sum(r-1)-self.sum(l-1)

    def add(self, i, x):
        """
        L[i] += x
        """
        while i <= self.size:
            self.L[i] += x
            i += i & (-i)

    def bisect(self,k:float)->int:
        """ binary search on BIT
        get index x s.t self.sum(,)>=k

        RETURN:
            res:index of x
        """
        k+=1 #convert k into 1-index

        res=0
        N=1
        while N<self.size:
            N*=2

        i=N//2
        while i>0:
            if(res+i<self.size and self.L[res+i]<k): #move to rignt on tree
                k-=self.L[res+i]
                res+=i
            #else move to left
            i//=2
        return res+1



N,Q = map(int,input().split())
C=list(map(int,input().split()))
pos=[]
for i in range(Q):
    l,r = map(int,input().split())
    pos.append([l,r,i])


pos=sorted(pos,key=lambda x:x[1])

last_appeared=[0]*(N+1)

B = BIT(N,0)

ans=[-1]*Q

cur_r=1
for l,r,i in pos:
    while cur_r<=r:
        last = last_appeared[C[cur_r-1]]
        if last==0:#first add
            B.add(cur_r,1)
        else:
            B.add(last,-1)
            B.add(cur_r,1)

        last_appeared[C[cur_r-1]]=cur_r #lastの更新
        cur_r+=1

    assert l>=1
    ans[i]=B.sum(r)-B.sum(l-1)


print("\n".join(map(str,ans)))

Buggy submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline
from collections import defaultdict
class BIT:
    """
    Binary Index Tree
    ###1-origin####

    add :L[i]+=x
    sum: sum(L[:l])
    range_sum : sum(L[l:r])

    #material http://hos.ac/slides/20140319_bit.pdf
    """

    def __init__(self, N, init_val=0):
        self.init_val = init_val
        self.size = N
        self.L = [init_val]*(N+1)

    def sum(self, r):
        """
        sum[,r)
        calc sum from L[0] to L[r-1]
        """
        ret = self.init_val
        while r > 0:
            ret += self.L[r]
            r -= r & (-r)

        return ret

    def range_sum(self, l, r):
        
        """
        idx周りが怪しい?
        sum[l,r)
        calc sum from L[l] to L[r-1]
        """
        return self.sum(r-1)-self.sum(l-1)

    def add(self, i, x):
        """
        L[i] += x
        """
        while i <= self.size:
            self.L[i] += x
            i += i & (-i)

    def bisect(self,k:float)->int:
        """ binary search on BIT
        get index x s.t self.sum(,)>=k

        RETURN:
            res:index of x
        """
        k+=1 #convert k into 1-index

        res=0
        N=1
        while N<self.size:
            N*=2

        i=N//2
        while i>0:
            if(res+i<self.size and self.L[res+i]<k): #move to rignt on tree
                k-=self.L[res+i]
                res+=i
            #else move to left
            i//=2
        return res+1



N,Q = map(int,input().split())
C=list(map(int,input().split()))


pos=[]
for i in range(Q):
    l,r = map(int,input().split())
    pos.append((l,r,i))


pos=sorted(pos,key=lambda x:x[1])

last_appeared=defaultdict(int)

B = BIT(N,0)

ans=[-1]*Q

cur_r=1
for l,r,i in pos:
    while cur_r<=r:
        last = last_appeared[C[cur_r]]
        if last==0:#first add
            B.add(cur_r,1)
        else:
            B.add(last,-1)
            B.add(cur_r,1)

        last_appeared[C[cur_r]]=cur_r #lastの更新
        cur_r+=1

    assert l>=1
    ans[i]=B.sum(r)-B.sum(l-1)


print("\n".join(map(str,ans)))