0303-range-sum-query-immutable.py

class NumArray:

    def __init__(self, nums: List[int]):
        self.prefix = []
        cur = 0
        for n in nums:
            cur += n
            self.prefix.append(cur)
        
        
    def sumRange(self, left: int, right: int) -> int:
        r = self.prefix[right] 
        l = self.prefix[left - 1] if left > 0 else 0
        return r - l