# LeetCode 1329. Sort the Matrix Diagonally in F#

## URL

leetcode.com/problems/sort-the-matrix-diago..

## Code

github.com/syohex/dotnet-study/tree/master/..

```
let diagonalSort (mat: int [,]) : int [,] =
let mutable m: Map<int, int list> = Map.empty
let rows = Array2D.length1 mat
let cols = Array2D.length2 mat
for i in 0 .. (rows - 1) do
for j in 0 .. (cols - 1) do
let key = i - j
match Map.tryFind key m with
| None -> m <- Map.add key [ mat[i, j] ] m
| Some (v) ->
let v' = (mat[i, j] :: v) |> List.sort
m <- Map.add key v' m
for i in 0 .. (rows - 1) do
for j in 0 .. (cols - 1) do
let key = i - j
match Map.find key m with
| [] -> failwith "never reach here"
| h :: t ->
mat.[i, j] <- h
m <- Map.add key t m
mat
```