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

Range Sum Query - Immutable

Total Accepted: 696 Total Submissions: 2406 Difficulty: Easy

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.

public class NumArray {
int[] sums;

public NumArray(int[] nums) {
sums = new int[nums.length];
System.arraycopy(nums, 0, sums, 0, nums.length);
for(int i=1; i<sums.length; i++) {
sums[i] += sums[i-1];
}
}

public int sumRange(int i, int j) {
if(i>j || i<0 || j<0 || j>=sums.length) return 0;
return i==0 ? sums[j] : (sums[j] - sums[i-1]);
}
}

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