Problem p02599 (python)

Fixed submission:
# Python3 code to find number of
# distinct numbers in a subarray
from sys import stdin,stdout
import sys
sys.setrecursionlimit(10**5)
MAX = 500001

def input():
    return stdin.readline().strip()
# structure to store queries
class Query:
    def __init__(self, l, r, idx):
        self.l = l
        self.r = r
        self.idx = idx


# updating the bit array
def update(idx, val, bit, n):
    while idx <= n:
        bit[idx] += val
        idx += idx & -idx


# querying the bit array
def query(idx, bit, n):
    summ = 0
    while idx:
        summ += bit[idx]
        idx -= idx & -idx
    return summ


def answeringQueries(arr, n, queries, q):
    # initialising bit array
    bit = [0] * (n + 1)

    # holds the rightmost index of
    # any number as numbers of a[i]
    # are less than or equal to 10^6
    last_visit = [-1] * MAX

    # answer for each query
    ans = [0] * q

    query_counter = 0
    for i in range(n):

        # If last visit is not -1 update -1 at the
        # idx equal to last_visit[arr[i]]
        if last_visit[arr[i]] != -1:
            update(last_visit[arr[i]] + 1, -1, bit, n)

        # Setting last_visit[arr[i]] as i and
        # updating the bit array accordingly
        last_visit[arr[i]] = i
        update(i + 1, 1, bit, n)

        # If i is equal to r of any query store answer
        # for that query in ans[]
        while query_counter < q and queries[query_counter].r == i:
            ans[queries[query_counter].idx] = \
                query(queries[query_counter].r + 1, bit, n) - \
                query(queries[query_counter].l, bit, n)
            query_counter += 1

    # print answer for each query
    for i in range(q):
        print(ans[i])


# Driver Code
if __name__ == "__main__":
    n, q = map(int, input().split())
    a = [int(k) for k in input().split()]
    queries = []
    for i in range(q):
        l, r = map(int, input().split())
        queries.append(Query(l-1, r-1, i))
    queries.sort(key=lambda x: x.r)
    answeringQueries(a, n, queries, q)

# This code is contributed by
# sanjeev2552

Buggy submission (verdict: Runtime Error):
# Python3 code to find number of
# distinct numbers in a subarray
MAX = 100001


# structure to store queries
class Query:
    def __init__(self, l, r, idx):
        self.l = l
        self.r = r
        self.idx = idx


# updating the bit array
def update(idx, val, bit, n):
    while idx <= n:
        bit[idx] += val
        idx += idx & -idx


# querying the bit array
def query(idx, bit, n):
    summ = 0
    while idx:
        summ += bit[idx]
        idx -= idx & -idx
    return summ


def answeringQueries(arr, n, queries, q):
    # initialising bit array
    bit = [0] * (n + 1)

    # holds the rightmost index of
    # any number as numbers of a[i]
    # are less than or equal to 10^6
    last_visit = [-1] * MAX

    # answer for each query
    ans = [0] * q

    query_counter = 0
    for i in range(n):

        # If last visit is not -1 update -1 at the
        # idx equal to last_visit[arr[i]]
        if last_visit[arr[i]] != -1:
            update(last_visit[arr[i]] + 1, -1, bit, n)

        # Setting last_visit[arr[i]] as i and
        # updating the bit array accordingly
        last_visit[arr[i]] = i
        update(i + 1, 1, bit, n)

        # If i is equal to r of any query store answer
        # for that query in ans[]
        while query_counter < q and queries[query_counter].r == i:
            ans[queries[query_counter].idx] = \
                query(queries[query_counter].r + 1, bit, n) - \
                query(queries[query_counter].l, bit, n)
            query_counter += 1

    # print answer for each query
    for i in range(q):
        print(ans[i])


# Driver Code
if __name__ == "__main__":
    n, q = map(int, input().split())
    a = [int(k) for k in input().split()]
    queries = []
    for i in range(q):
        l, r = map(int, input().split())
        queries.append(Query(l-1, r-1, i))
    queries.sort(key=lambda x: x.r)
    answeringQueries(a, n, queries, q)

# This code is contributed by
# sanjeev2552