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;
}
}
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