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]
]
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 ]
vector<int> getModifiedArray(int length, vector<vector<int>>& updates) {
vector<int> ret(length, );
for (int i = ; i < updates.size(); i++) {
ret[updates[i][]] += updates[i][];
int endIdx = updates[i][] + ;
if (endIdx < length)
ret[endIdx] -= updates[i][];
}
for (int i = ; i < length; i++) {
ret[i] += ret[i - ];
}
return ret;
}