Range Addition

Assume you have an array of length n initialized with all 0's and are given k update operations.

Each operation is represented as a triplet: [startIndex, endIndex, inc] which increments each element of subarray A[startIndex ... endIndex] (startIndex and endIndex inclusive) with inc.

Return the modified array after all k operations were executed.

Example

Given:
length = 5,
updates = 
[
[1,  3,  2],
[2,  4,  3],
[0,  2, -2]
]
return [-2, 0, 3, 5, 3]

Explanation:
Initial state:
[ 0, 0, 0, 0, 0 ]
After applying operation [1, 3, 2]:
[ 0, 2, 2, 2, 0 ]
After applying operation [2, 4, 3]:
[ 0, 2, 5, 5, 3 ]
After applying operation [0, 2, -2]:
[-2, 0, 3, 5, 3 ]

public class Solution {
    public int[] getModifiedArray(int length, int[][] updates) {
        int[] ans = new int[length];
        for (int[] query : updates) {
            ans[query[0]] += query[2];
            if (query[1] + 1 < length)
                ans[query[1] + 1] -= query[2];
        }
        // Converting to Prefix sum to convert our updates effect into whole array
        int sum = 0;
        for (int i = 0; i < length; i++) {
            sum += ans[i];
            ans[i] = sum;
        }
        return ans;
    }
}