commit

Author: 王俊超

Diff for: .gitignore

@@ -0,0 +1,4 @@
+# Created by .ignore support plugin (hsz.mobi)
+*.iml
+.idea
+

Diff for: .idea/modules.xml

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+/**
+ * @author: wangjunchao(王俊超)
+ * @time: 2018-09-28 15:06
+ **/
+public class Solution {
+    public void solveSudoku(char[][] board) {
+        if(board == null || board.length == 0) {
+            return;
+        }
+        solve(board);
+    }
+
+    public boolean solve(char[][] board){
+        for(int i = 0; i < board.length; i++){
+            for(int j = 0; j < board[0].length; j++){
+                if(board[i][j] == '.'){
+                    // 尝试1到9的数字
+                    for(char c = '1'; c <= '9'; c++){
+                        if(isValid(board, i, j, c)){
+                            // 将字符放入单元格
+                            board[i][j] = c;
+
+                            // 如果字符可以放入单元格返回true
+                            if(solve(board)){
+                                return true;
+                            }else { // 如果字符不能放入单元格就是还原成点号
+                                board[i][j] = '.';
+                            }
+                        }
+                    }
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    private boolean isValid(char[][] board, int row, int col, char c){
+        for(int i = 0; i < 9; i++) {
+            // 检查行
+            if(board[i][col] != '.' && board[i][col] == c) {
+                return false;
+            }
+            // 检查列
+            if(board[row][i] != '.' && board[row][i] == c) {
+                return false;
+            }
+            // 检查3*3的单元格
+            if(board[3 * (row / 3) + i / 3][ 3 * (col / 3) + i % 3] != '.'
+                    && board[3 * (row / 3) + i / 3][3 * (col / 3) + i % 3] == c) {
+                return false;
+            }
+        }
+        return true;
+    }
+}