1329. Sort the Matrix Diagonally#
A matrix diagonal is a diagonal line from some element in the top-left to some element in the bottom-right of the matrix. For example, the matrix mat with dimensions 6 x 3 has a matrix diagonal starting from mat[2][0], going through mat[3][1], and ending at 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.lengthn == mat[i].length1 <= m, n <= 1001 <= mat[i][j] <= 100
Simulation#
class Solution {
public:
vector<vector<int>> diagonalSort(vector<vector<int>> &mat) {
/*
00 01 02 03
10 11 12 13
20 21 22 23
*/
/*
{3,3,1,1},
{2,2,1,2},
{1,1,1,2}
*/
int m = mat.size(), n = mat[0].size();
// Traverse horizontally
for (int i = 0; i < n; ++i) {
int x = 0, y = i;
vector<int> line;
while (x < m && y < n) {
line.push_back(mat[x][y]);
++x;
++y;
}
sort(line.begin(), line.end());
x = 0, y = i;
while (x < m && y < n) {
mat[x][y] = line[x];
++x;
++y;
}
}
// Traverse vertically
for (int j = 1; j < m; ++j) {
int x = j, y = 0;
vector<int> line;
while (x < m && y < n) {
line.push_back(mat[x++][y++]);
}
sort(line.begin(), line.end());
x = j, y = 0;
while (x < m && y < n) {
mat[x][y] = line[y];
++x;
++y;
}
}
return mat;
}
};