Today's Challenge

https://leetcode.com/problems/range-sum-query-mutable/

Range Sum Query - Mutable - LeetCode

처음에 좀 navie 하게 풀었다가 TL 남 =_=
솔루션 좀 찾아보니 미리 저장해놓는 방식으로 해결 가능.

class NumArray:

    def __init__(self, nums: List[int]):
        self.nums = nums
        self.s = sum(nums)
        self.l = len(nums)

    def update(self, index: int, val: int) -> None:
        self.s -= self.nums[index]
        self.nums[index] = val
        self.s += self.nums[index]

    def sumRange(self, left: int, right: int) -> int:
        if right - left > self.l // 2:
            ans = sum(self.nums[:left]) + sum(self.nums[right+1:])
            return self.s - ans
        else:
            return sum(self.nums[left: right+1])