Add solution and test-cases for problem 3446

Author: 0xff-dev

leetcode/3401-3500/3446.Sort-Matrix-by-Diagonals/1.png

@@ -1,28 +1,57 @@
 # [3446.Sort Matrix by Diagonals][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+You are given an `n x n` square matrix of integers `grid`. Return the matrix such that:
+
+- The diagonals in the **bottom-left triangle** (including the middle diagonal) are sorted in **non-increasing order**.
+- The diagonals in the **top-right triangle** are sorted in **non-decreasing order**.
+
+**Example 1:** 
+
+![1](./1.png)
+
+```
+Input: grid = [[1,7,3],[9,8,2],[4,5,6]]
+
+Output: [[8,2,3],[9,6,7],[4,5,1]]
+
+Explanation:
+
+The diagonals with a black arrow (bottom-left triangle) should be sorted in non-increasing order:
 
-**Example 1:**
+[1, 8, 6] becomes [8, 6, 1].
+[9, 5] and [4] remain unchanged.
+The diagonals with a blue arrow (top-right triangle) should be sorted in non-decreasing order:
 
+[7, 2] becomes [2, 7].
+[3] remains unchanged.
 ```
-Input: a = "11", b = "1"
-Output: "100"
+
+**Example 2:** 
+
+![2](./2.png)
+
 ```
+Input: grid = [[0,1],[1,2]]
 
-## 题意
-> ...
+Output: [[2,1],[1,0]]
 
-## 题解
+Explanation:
 
-### 思路1
-> ...
-Sort Matrix by Diagonals
-```go
+The diagonals with a black arrow must be non-increasing, so [0, 2] is changed to [2, 0]. The other diagonals are already in the correct order.
 ```
 
+**Example 3:**
+
+```
+Input: grid = [[1]]
+
+Output: [[1]]
+
+Explanation:
+
+Diagonals with exactly one element are already in order, so no changes are needed.
+```
 
 ## 结语
 

leetcode/3401-3500/3446.Sort-Matrix-by-Diagonals/2.png

@@ -1,5 +1,33 @@
 package Solution
 
-func Solution(x bool) bool {
-return x
+import "sort"
+
+func Solution(grid [][]int) [][]int {
+n := len(grid)
+for i := 0; i < n; i++ {
+// j = 0
+have := []int{}
+for r, j := i, 0; r < n; r, j = r+1, j+1 {
+have = append(have, grid[r][j])
+}
+sort.Slice(have, func(i, j int) bool {
+return have[i] > have[j]
+})
+index := 0
+for r, j := i, 0; r < n; r, j, index = r+1, j+1, index+1 {
+grid[r][j] = have[index]
+}
+}
+for j := 1; j < n; j++ {
+// i = 1
+have := []int{}
+for i, r := 0, j; r < n; i, r = i+1, r+1 {
+have = append(have, grid[i][r])
+}
+sort.Ints(have)
+for i, r, index := 0, j, 0; r < n; i, r, index = i+1, r+1, index+1 {
+grid[i][r] = have[index]
+}
+}
+return grid
 }

leetcode/3401-3500/3446.Sort-Matrix-by-Diagonals/README.md

@@ -10,12 +10,12 @@ func TestSolution(t *testing.T) {
 //	测试用例
 cases := []struct {
 name string
-inputs bool
-expect bool
+inputs [][]int
+expect [][]int
 }{
-{"TestCase", true, true},
-{"TestCase", true, true},
-{"TestCase", false, false},
+{"TestCase1", [][]int{{1, 7, 3}, {9, 8, 2}, {4, 5, 6}}, [][]int{{8, 2, 3}, {9, 6, 7}, {4, 5, 1}}},
+{"TestCase2", [][]int{{0, 1}, {1, 2}}, [][]int{{2, 1}, {1, 0}}},
+{"TestCase3", [][]int{{1}}, [][]int{{1}}},
 }
 
 //	开始测试
@@ -30,10 +30,10 @@ func TestSolution(t *testing.T) {
 }
 }
 
-//压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//使用案列
+// 使用案列
 func ExampleSolution() {
 }