Update 0051.N皇后.md

problems/0051.N皇后.md

@@ -363,7 +363,72 @@ Python：
 
 
 Go：
+```Go
+import "strings"
+var res [][]string
 
+func isValid(board [][]string, row, col int) (res bool){
+    n := len(board)
+    for i:=0; i < row; i++ {
+        if board[i][col] == "Q" {
+            return false
+        }
+    }
+    for i := 0; i < n; i++{
+        if board[row][i] == "Q" {
+            return false
+        }
+    }
+
+    for i ,j := row, col; i >= 0 && j >=0 ; i, j = i - 1, j- 1{
+        if board[i][j] == "Q"{
+            return false
+        }
+    }
+    for i, j := row, col; i >=0 && j < n; i,j = i-1, j+1 {
+        if board[i][j] == "Q" {
+            return false
+        }
+    }
+    return true
+}
+
+func backtrack(board [][]string, row int) {
+    size := len(board)
+    if row == size{
+        temp := make([]string, size)
+        for i := 0; i<size;i++{
+            temp[i] = strings.Join(board[i],"")
+        }
+        res =append(res,temp)
+        return 
+    }
+    for col := 0; col < size; col++ {
+        if !isValid(board, row, col){
+            continue
+        }
+        board[row][col] = "Q"
+        backtrack(board, row+1)
+        board[row][col] = "."
+    }
+}
+
+func solveNQueens(n int) [][]string {
+    res = [][]string{}
+    board := make([][]string, n)
+    for i := 0; i < n; i++{
+        board[i] = make([]string, n)
+    }
+    for i := 0; i < n; i++{
+        for j := 0; j<n;j++{
+            board[i][j] = "."
+        }
+    }
+    backtrack(board, 0)
+
+    return res
+}
+```