370. Range Addition

JIAKAOBO

LeetCode

感谢赞助!

• ㊗️
• 大家
• offer
• 多多！

Problem

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:

Input: length = 5, updates = [[1,3,2],[2,4,3],[0,2,-2]]
Output: [-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]

Code

class Solution {
    public int[] getModifiedArray(int length, int[][] updates) {
        int[] res = new int[length];

        for(int[] update : updates) {
            res[update[0]] += update[2];
            if(update[1] < length - 1) {
                res[update[1] + 1] -= update[2];
            }
        }

        int curr = res[0];
        for(int i = 1; i < length; i++) {
            res[i] += curr;
            curr = res[i];
        }

        return res;
    }
}