303. Range Sum Query

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.

本题比较简单，代码如下：

 1 public class NumArray {
 2     int[] sum;
 3     public NumArray(int[] nums) {
 4         sum = new int[nums.length+1];
 5         for(int i=0;i<nums.length;i++){
 6             sum[i+1] = sum[i]+nums[i];
 7         }
 8     }
 9     
10     public int sumRange(int i, int j) {
11         return sum[j+1]-sum[i];
12     }
13 }
14 
15 /**
16  * Your NumArray object will be instantiated and called as such:
17  * NumArray obj = new NumArray(nums);
18  * int param_1 = obj.sumRange(i,j);
19  */