303. Range Sum Query

Given an integer array nums, find the sum of the elements between indicesi and j (i ≤ j), inclusive.

Example:

Given nums = [-2, 0, 3, -5, 2, -1]sumRange(0, 2) -> 1sumRange(2, 5) -> -1sumRange(0, 5) -> -3

Note:

1. You may assume that the array does not change.
2. There are many calls to sumRange function.

代码：

class NumArray {

   int[] arrays;
    public NumArray(int[] nums) {
        arrays=new int[nums.length+1];
        int sum=0;
        for(int i=0;i<nums.length;i++)
        {
            arrays[i]=sum;
            sum+=nums[i];
        }
        arrays[nums.length]=sum;
    }
    
    public int sumRange(int i, int j) {
        return arrays[j+1]-arrays[i];
    }


}