[LeetCode]303. Range Sum Query - Immutable

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

Given nums = [-2, 0, 3, -5, 2, -1]

sumRange(0, 2) -> 1
sumRange(2, 5) -> -1
sumRange(0, 5) -> -3

Note:

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

类型：Dynamic Programming

public class NumArray {

private int[] sums;
public NumArray(int[] nums) {
sums = new int[nums.length+1];
for(int i=1; i<nums.length+1; i++)
sums[i]=nums[i-1]+sums[i-1];
}

public int sumRange(int i, int j) {

return sums[j+1]-sums[i];
}
}

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

注意下标