feat: add solutions to lc problem: No.52 (#2471)

No.0052.N-Queens II

Author: yanglbme

solution/0000-0099/0046.Permutations/README_EN.md

@@ -48,6 +48,28 @@ class Solution:
         return list(permutations(nums))
 ```
 
+```python
+class Solution:
+    def permute(self, nums: List[int]) -> List[List[int]]:
+        def dfs(i):
+            if i == n:
+                ans.append(t[:])
+                return
+            for j in range(n):
+                if not vis[j]:
+                    vis[j] = True
+                    t[i] = nums[j]
+                    dfs(i + 1)
+                    vis[j] = False
+
+        n = len(nums)
+        vis = [False] * n
+        t = [0] * n
+        ans = []
+        dfs(0)
+        return ans
+```
+
 ```java
 class Solution {
     private List<List<Integer>> ans = new ArrayList<>();

solution/0000-0099/0052.N-Queens II/README.md

@@ -198,6 +198,36 @@ function totalNQueens(n: number): number {
 }
 ```
 
+```cs
+public class Solution {
+    public int TotalNQueens(int n) {
+        bool[] cols = new bool[10];
+        bool[] dg = new bool[20];
+        bool[] udg = new bool[20];
+        int ans = 0;
+
+        void dfs(int i) {
+            if (i == n) {
+                ans++;
+                return;
+            }
+            for (int j = 0; j < n; j++) {
+                int a = i + j, b = i - j + n;
+                if (cols[j] || dg[a] || udg[b]) {
+                    continue;
+                }
+                cols[j] = dg[a] = udg[b] = true;
+                dfs(i + 1);
+                cols[j] = dg[a] = udg[b] = false;
+            }
+        }
+
+        dfs(0);
+        return ans;
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

solution/0000-0099/0052.N-Queens II/README_EN.md

@@ -190,6 +190,36 @@ function totalNQueens(n: number): number {
 }
 ```
 
+```cs
+public class Solution {
+    public int TotalNQueens(int n) {
+        bool[] cols = new bool[10];
+        bool[] dg = new bool[20];
+        bool[] udg = new bool[20];
+        int ans = 0;
+
+        void dfs(int i) {
+            if (i == n) {
+                ans++;
+                return;
+            }
+            for (int j = 0; j < n; j++) {
+                int a = i + j, b = i - j + n;
+                if (cols[j] || dg[a] || udg[b]) {
+                    continue;
+                }
+                cols[j] = dg[a] = udg[b] = true;
+                dfs(i + 1);
+                cols[j] = dg[a] = udg[b] = false;
+            }
+        }
+
+        dfs(0);
+        return ans;
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

solution/0000-0099/0052.N-Queens II/Solution.cs

@@ -0,0 +1,27 @@
+public class Solution {
+    public int TotalNQueens(int n) {
+        bool[] cols = new bool[10];
+        bool[] dg = new bool[20];
+        bool[] udg = new bool[20];
+        int ans = 0;
+
+        void dfs(int i) {
+            if (i == n) {
+                ans++;
+                return;
+            }
+            for (int j = 0; j < n; j++) {
+                int a = i + j, b = i - j + n;
+                if (cols[j] || dg[a] || udg[b]) {
+                    continue;
+                }
+                cols[j] = dg[a] = udg[b] = true;
+                dfs(i + 1);
+                cols[j] = dg[a] = udg[b] = false;
+            }
+        }
+
+        dfs(0);
+        return ans;
+    }
+}