From 5b48986cff4b1b89ca25fd18d15f8819beb409c4 Mon Sep 17 00:00:00 2001
From: markilue <745518019@qq.com>
Date: Fri, 3 Feb 2023 22:02:06 +0800
Subject: [PATCH] =?UTF-8?q?leecode=E6=9B=B4=E6=96=B0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 ...{SolveSudoku.java => T14_SolveSudoku.java} |   2 +-
 .../backtrace/second/T14_SolveSudoku.java     | 104 ++++++++++++++++++
 2 files changed, 105 insertions(+), 1 deletion(-)
 rename Leecode/src/main/java/com/markilue/leecode/backtrace/{SolveSudoku.java => T14_SolveSudoku.java} (99%)
 create mode 100644 Leecode/src/main/java/com/markilue/leecode/backtrace/second/T14_SolveSudoku.java

diff --git a/Leecode/src/main/java/com/markilue/leecode/backtrace/SolveSudoku.java b/Leecode/src/main/java/com/markilue/leecode/backtrace/T14_SolveSudoku.java
similarity index 99%
rename from Leecode/src/main/java/com/markilue/leecode/backtrace/SolveSudoku.java
rename to Leecode/src/main/java/com/markilue/leecode/backtrace/T14_SolveSudoku.java
index 0a81234..d63fbf1 100644
--- a/Leecode/src/main/java/com/markilue/leecode/backtrace/SolveSudoku.java
+++ b/Leecode/src/main/java/com/markilue/leecode/backtrace/T14_SolveSudoku.java
@@ -20,7 +20,7 @@ import java.util.List;
  * 数独部分空格内已填入了数字，空白格用 '.' 表示。
  * @Version: 1.0
  */
-public class SolveSudoku {
+public class T14_SolveSudoku {
 
     @Test
     public void test() {
diff --git a/Leecode/src/main/java/com/markilue/leecode/backtrace/second/T14_SolveSudoku.java b/Leecode/src/main/java/com/markilue/leecode/backtrace/second/T14_SolveSudoku.java
new file mode 100644
index 0000000..1ccb135
--- /dev/null
+++ b/Leecode/src/main/java/com/markilue/leecode/backtrace/second/T14_SolveSudoku.java
@@ -0,0 +1,104 @@
+package com.markilue.leecode.backtrace.second;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+
+/**
+ *@BelongsProject: Leecode
+ *@BelongsPackage: com.markilue.leecode.backtrace.second
+ *@Author: dingjiawen
+ *@CreateTime: 2023-02-03  20:35
+ *@Description:
+ * TODO  力扣37题  解数独:
+ *  编写一个程序，通过填充空格来解决数独问题。
+ *  数独的解法需 遵循如下规则：
+ *   数字 1-9 在每一行只能出现一次。
+ *   数字 1-9 在每一列只能出现一次。
+ *   数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。（请参考示例图）
+ *   数独部分空格内已填入了数字，空白格用 '.' 表示。
+ *@Version: 1.0
+ */
+public class T14_SolveSudoku {
+
+    @Test
+    public void test() {
+        char[][] board = {
+                {'5', '3', '.', '.', '7', '.', '.', '.', '.'},
+                {'6', '.', '.', '1', '9', '5', '.', '.', '.'},
+                {'.', '9', '8', '.', '.', '.', '.', '6', '.'},
+                {'8', '.', '.', '.', '6', '.', '.', '.', '3'},
+                {'4', '.', '.', '8', '.', '3', '.', '.', '1'},
+                {'7', '.', '.', '.', '2', '.', '.', '.', '6'},
+                {'.', '6', '.', '.', '.', '.', '2', '8', '.'},
+                {'.', '.', '.', '4', '1', '9', '.', '.', '5'},
+                {'.', '.', '.', '.', '8', '.', '.', '7', '9'}};
+
+        solveSudoku(board);
+        for (int i = 0; i < board.length; i++) {
+            System.out.println(Arrays.toString(board[i]));
+        }
+    }
+
+    public void solveSudoku(char[][] board) {
+        backtracking(board,0,0);
+
+    }
+
+    public boolean backtracking(char[][] board, int row, int col) {
+        if (row == board.length) {
+            return true;
+        } else if (col == board.length) {
+            //这一行填完了，填下一行
+            return backtracking(board, row + 1, 0);
+        } else if (board[row][col] != '.') {
+            //这个位置有数字了,填下一个
+            return backtracking(board, row, col + 1);
+        }
+
+        for (int i = 1; i <= 9; i++) {
+            //填入board[row][col]的数字i
+            if (isFit(board, row, col, i)) {
+                board[row][col] = (char) (i + '0');
+                if (backtracking(board, row, col + 1)) {
+                    //返回是true,不用继续遍历了,直接返回
+                    return true;
+                }
+                //false的话重新尝试新数字
+                board[row][col] = '.';
+            }
+        }
+        //全都试完了都不对
+        return false;
+    }
+
+    private boolean isFit(char[][] board, int row, int col, int n) {
+        //
+        char num =(char) (n + '0');
+        //检查行
+        for (int i = 0; i < 9; i++) {
+            if (board[i][col] == num) {
+                return false;
+            }
+        }
+
+        //检查列
+        for (int i = 0; i < 9; i++) {
+            if (board[row][i] == num) {
+                return false;
+            }
+        }
+        //检查九宫格
+        int baseRow = row - (row % 3);
+        int baseCol = col - (col % 3);
+        for (int i = 0; i < 3; i++) {
+            for (int j = 0; j < 3; j++) {
+                if (board[baseRow + i][baseCol + j] == num) {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+}