Today I have done leetcode's November LeetCoding Challenge with cpp.

November LeetCoding Challenge 14

Description

Increment Submatrices by One

You are given a positive integer n, indicating that we initially have an n x n 0-indexed integer matrix mat filled with zeroes.

You are also given a 2D integer array query. For each query[i] = [row1i, col1i, row2i, col2i], you should do the following operation:

• Add 1 to every element in the submatrix with the top left corner (row1i, col1i) and the bottom right corner (row2i, col2i). That is, add 1 to mat[x][y] for all row1i <= x <= row2i and col1i <= y <= col2i.

Return the matrix mat after performing every query.

Example 1:

Input: n = 3, queries = [[1,1,2,2],[0,0,1,1]]
Output: [[1,1,0],[1,2,1],[0,1,1]]
Explanation: The diagram above shows the initial matrix, the matrix after the first query, and the matrix after the second query.
- In the first query, we add 1 to every element in the submatrix with the top left corner (1, 1) and bottom right corner (2, 2).
- In the second query, we add 1 to every element in the submatrix with the top left corner (0, 0) and bottom right corner (1, 1).

Example 2:

Input: n = 2, queries = [[0,0,1,1]]
Output: [[1,1],[1,1]]
Explanation: The diagram above shows the initial matrix and the matrix after the first query.
- In the first query we add 1 to every element in the matrix.

Constraints:

• 1 <= n <= 500
• 1 <= queries.length <= 104
• 0 <= row1i <= row2i < n
• 0 <= col1i <= col2i < n

Solution

class Solution {
public:
  vector<vector<int>> rangeAddQueries(int n, vector<vector<int>>& queries) {
    vector<vector<int>> answer(n + 1, vector<int>(n + 1));
    for(const auto &q : queries) {
      answer[q[0]][q[1]] += 1;
      answer[q[2] + 1][q[1]] -= 1;
      answer[q[2] + 1][q[3] + 1] += 1;
      answer[q[0]][q[3] + 1] -= 1;
    }
    for(int i = 0; i < n ; ++i) {
      for(int j = 1; j < n; ++j) {
        answer[i][j] += answer[i][j - 1];
      }
    }
    for(int i = 1; i < n; ++i) {
      for(int j = 0; j < n; ++j) {
        answer[i][j] += answer[i - 1][j];
      }
    }
    for(auto &row : answer) {
      row.resize(n);
    }
    answer.resize(n);
    return answer;
  }
};

// Accepted
// 31/31 cases passed (24 ms)
// Your runtime beats 70.41 % of cpp submissions
// Your memory usage beats 58.57 % of cpp submissions (86.6 MB)