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.

Solution

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 m = i; m <= j; m++) {
            sum += nums[m];
        }

        return sum;
    }
}