====== 커피숍2 ======

===== 풀이 =====
  * 구간합과 포인트 업데이트를 번갈아서 처리해주면 되는 기본적인 [[ps:구간 쿼리#구간합|구간합 쿼리]] 문제.
  * Fenwick tree를 이용하면 초기화에 O(n), 각 쿼리 하나 처리에 O(logn)이 걸린다. 총 시간복잡도는 O(n+mlogn)

===== 코드 =====
<dkpr py>
"""Solution code for "BOJ 1275. 커피숍2".

- Problem link: https://www.acmicpc.net/problem/1275
- Solution link: http://www.teferi.net/ps/problems/boj/1275

Tags: [Fenwick tree]
"""

import sys
from teflib import fenwicktree


def main():
    # pylint: disable=unused-variable
    N, Q = [int(x) for x in sys.stdin.readline().split()]
    nums = [int(x) for x in sys.stdin.readline().split()]
    fenwick = fenwicktree.FenwickTree(nums)
    for _ in range(Q):
        x, y, a, b = [int(x) for x in sys.stdin.readline().split()]
        print(fenwick.query(x - 1, y) if x < y else fenwick.query(y - 1, x))
        fenwick.set(a - 1, b)


if __name__ == '__main__':
    main()
</dkpr>
  * Dependency: [[:ps:teflib:fenwicktree#FenwickTree|teflib.fenwicktree.FenwickTree]]

{{tag>BOJ ps:problems:boj:골드_1}}