Poj2676

经典DFS现在看来nice啊！

 package SoduKu;

 import java.io.InputStreamReader;
 import java.util.Scanner;
 /*
  *我用row[k][i]表示第k行是否已经有数i
  *col[k][i]表示第k列是否已经有数i
  *而sq[k][i]表示第k个九宫格是否有数i（这里k=(x/3)*3+(y/3),可以想想为什么）
  *从0,0 依次搜到8,8  DFS依次往下
  **/
 public class Poj2676{

     static int[][] map = new int[9][9];
     static int[][] col = new int[9][9];
     static int[][] row = new int[9][9];
     static int[][] sq  = new int[9][9];
     static boolean isFind = false;
     static void fill(int[][] a){
         for(int i = 0; i < 9; ++i){
             for(int j = 0; j < 9; ++j)
                 a[i][j] = 0;
         }
     }
     static void print(){
         for(int i = 0; i < 9; ++i) {
             for(int j = 0; j < 9; ++j){
                 System.out.print(map[i][j]+1);
             }
             System.out.println();
         }
     }

     static void dfs(int x, int y){
         int u = x*9 + y + 1;
         if(x == 9){
             isFind = true;
             print();
         }

         if(isFind)
             return;
         if(map[x][y] != -1){
             dfs(u/9, u%9);
             return;
         }

         for(int i = 0; i < 9 && !isFind; ++i){
             int k = (x/3)*3 + y/3;
             if(row[x][i] == 0 && col[y][i] == 0 && sq[k][i] == 0){
                 row[x][i] = col[y][i] = sq[k][i] = 1;
                 map[x][y] = i;

                 dfs(u/9, u%9);

                 row[x][i] = col[y][i] = sq[k][i] = 0;
                 map[x][y] = -1;
             }
         }
     }
     public static void main(String[] args){
         Scanner scanner = new Scanner(new InputStreamReader(System.in));

         int k;
         int n = scanner.nextInt();
         scanner.nextLine();
         for(int ni = 1; ni <= n; ++ni){

             fill(map);
             fill(row);
             fill(col);
             fill(sq);
             isFind = false;
             for(int i = 0; i < 9; ++i){
                 String string = scanner.nextLine();
                 for(int j = 0; j < 9; ++j) {
                     k = string.charAt(j) - '0';
                     map[i][j] = k-1;
                     if(k != 0){
                         row[i][k-1] = col[j][k-1] = sq[(i/3)*3 + (j/3)][k-1] = 1;
                     }
                 }
             }
             dfs(0, 0);
         }
     }
 }