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

Note:

1. You may assume that the array does not change.

1. There are many calls to sumRange function.

// Your NumArray object will be instantiated and called as such:
// NumArray numArray = new NumArray(nums);
// numArray.sumRange(0, 1);
// numArray.sumRange(1, 2);

思路:根据他的调用，无非就是添加一个钩子方法

代人如下(已通过leetcode)

public class NumArray {
private int[]nums;
   public NumArray(int[] nums) {
       this.nums=nums;
   }


   public int sumRange(int i, int j) {
    int sum=0;
    for(int k=i;k<=j;k++) {
    sum+=nums[k];
    }
    return sum;
   }
}