leetcode303

public class NumArray
    {
        List<int> list = new List<int>();
        public NumArray(int[] nums)
        {
            var sum = ;
            for (int i = ; i < nums.Length; i++)
            {
                sum += nums[i];
                list.Add(sum);
            }
        }

        public int SumRange(int i, int j)
        {
            if (i == )
            {
                return list[j];
            }
            else
            {
                return list[j] - list[i - ];
            }
        }
    }

/**
 * Your NumArray object will be instantiated and called as such:
 * NumArray obj = new NumArray(nums);
 * int param_1 = obj.SumRange(i,j);
 */

https://leetcode.com/problems/range-sum-query-immutable/#/description

补充一个python的实现：

 from itertools import accumulate
 class NumArray:

     def __init__(self, nums: List[int]):
         self.dp = list(accumulate(nums))

     def sumRange(self, i: int, j: int) -> int:
         if i == :
             return self.dp[j]
         else:
             return self.dp[j] - self.dp[i-]