1329. Sort the Matrix Diagonally

Description

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

Solutions

• class Solution {
public int[][] diagonalSort(int[][] mat) {
int m = mat.length, n = mat[0].length;
for (int k = 0; k < Math.min(m, n) - 1; ++k) {
for (int i = 0; i < m - 1; ++i) {
for (int j = 0; j < n - 1; ++j) {
if (mat[i][j] > mat[i + 1][j + 1]) {
int t = mat[i][j];
mat[i][j] = mat[i + 1][j + 1];
mat[i + 1][j + 1] = t;
}
}
}
}
return mat;
}
}

• class Solution {
public:
vector<vector<int>> diagonalSort(vector<vector<int>>& mat) {
int m = mat.size(), n = mat[0].size();
for (int k = 0; k < min(m, n) - 1; ++k)
for (int i = 0; i < m - 1; ++i)
for (int j = 0; j < n - 1; ++j)
if (mat[i][j] > mat[i + 1][j + 1])
swap(mat[i][j], mat[i + 1][j + 1]);
return mat;
}
};

• class Solution:
def diagonalSort(self, mat: List[List[int]]) -> List[List[int]]:
m, n = len(mat), len(mat[0])
for k in range(min(m, n) - 1):
for i in range(m - 1):
for j in range(n - 1):
if mat[i][j] > mat[i + 1][j + 1]:
mat[i][j], mat[i + 1][j + 1] = mat[i + 1][j + 1], mat[i][j]
return mat

• func diagonalSort(mat [][]int) [][]int {
m, n := len(mat), len(mat[0])
for k := 0; k < m-1 && k < n-1; k++ {
for i := 0; i < m-1; i++ {
for j := 0; j < n-1; j++ {
if mat[i][j] > mat[i+1][j+1] {
mat[i][j], mat[i+1][j+1] = mat[i+1][j+1], mat[i][j]
}
}
}
}
return mat
}

• function diagonalSort(mat: number[][]): number[][] {
const [m, n] = [mat.length, mat[0].length];
const g: number[][] = Array.from({ length: m + n }, () => []);
for (let i = 0; i < m; ++i) {
for (let j = 0; j < n; ++j) {
g[m - i + j].push(mat[i][j]);
}
}
for (const e of g) {
e.sort((a, b) => b - a);
}
for (let i = 0; i < m; ++i) {
for (let j = 0; j < n; ++j) {
mat[i][j] = g[m - i + j].pop()!;
}
}
return mat;
}

• public class Solution {
public int[][] DiagonalSort(int[][] mat) {
int m = mat.Length;
int n = mat[0].Length;
List<List<int>> g = new List<List<int>>();
for (int i = 0; i < m + n; i++) {
g.Add(new List<int>());
}
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
g[m - i + j].Add(mat[i][j]);
}
}
foreach (var e in g) {
e.Sort((a, b) => b.CompareTo(a));
}
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
int val = g[m - i + j][g[m - i + j].Count - 1];
g[m - i + j].RemoveAt(g[m - i + j].Count - 1);
mat[i][j] = val;
}
}
return mat;
}
}

• impl Solution {
pub fn diagonal_sort(mut mat: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
let m = mat.len();
let n = mat[0].len();
let mut g: Vec<Vec<i32>> = vec![vec![]; m + n];
for i in 0..m {
for j in 0..n {
g[m - i + j].push(mat[i][j]);
}
}
for e in &mut g {
e.sort_by(|a, b| b.cmp(a));
}
for i in 0..m {
for j in 0..n {
mat[i][j] = g[m - i + j].pop().unwrap();
}
}
mat
}
}