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

August LeetCoding Challenge 28

Description

Sort the Matrix Diagonally

A matrix diagonal is a diagonal line of cells starting from some cell in either the topmost row or leftmost column and going in the bottom-right direction until reaching the matrix's end. For example, the matrix diagonal starting from mat[2][0], where mat is a 6 x 3 matrix, includes cells mat[2][0], mat[3][1], and mat[4][2].

Given an m x n matrix mat of integers, sort each matrix diagonal in ascending order and return the resulting matrix.

Example 1:

Input: mat = [[3,3,1,1],[2,2,1,2],[1,1,1,2]]
Output: [[1,1,1,1],[1,2,2,2],[1,2,3,3]]

Example 2:

Input: mat = [[11,25,66,1,69,7],[23,55,17,45,15,52],[75,31,36,44,58,8],[22,27,33,25,68,4],[84,28,14,11,5,50]]
Output: [[5,17,4,1,52,7],[11,11,25,45,8,69],[14,23,25,44,58,15],[22,27,31,36,50,66],[84,28,75,33,55,68]]

Constraints:

• m == mat.length
• n == mat[i].length
• 1 <= m, n <= 100
• 1 <= mat[i][j] <= 100

Solution

class Solution {
public:
  vector<vector<int>> diagonalSort(vector<vector<int>>& mat) {
    int rows = mat.size();
    int cols = mat.front().size();
    for(int i = 0; i < rows+cols-1; ++i) {
      int rowBegin = max(0, i+1-cols);
      int colBegin = rowBegin == 0 ? cols - 1 - i : 0;
      // cout << '#' << rowBegin << ' ' << colBegin << endl;
      for(int index = 0; rowBegin + index < rows-1 && colBegin + index < cols-1; ++index) {
        for(int j = 1; rowBegin + j < rows-index && colBegin + j < cols-index; ++j) {
          // cout << rowBegin + j << ' ' << colBegin + j << endl;
          if(mat[rowBegin+j][colBegin+j] < mat[rowBegin+j-1][colBegin+j-1]) {
            swap(mat[rowBegin+j][colBegin+j], mat[rowBegin+j-1][colBegin+j-1]);
          }
        }
      }
    }
    return move(mat);
  }
};

// Accepted
// 15/15 cases passed (33 ms)
// Your runtime beats 10.63 % of cpp submissions
// Your memory usage beats 99.93 % of cpp submissions (8.4 MB)