做了很久还是参考了别人的答案orz，其实也不难啊。我要开始学一下怎么写搜索了。。。
题目链接：poj2676 Sudoku
题解：暴力搜索，DFS每个空白格子所放数字。
1 #include<cstdio> 2 #include<iostream> 3 #include<cstring> 4 #include<algorithm> 5 #include<vector> 6 using namespace std; 7 bool row_f[9][10];//row_f[i][j]=1表示第i行已经放了数字j 8 bool col_f[9][10]; 9 bool block_f[9][10]; 10 int g[9][9]; 11 struct blank{ 12 int i, j; 13 blank(int i, int j):i(i),j(j) {} 14 }; 15 vector<blank> bk; 16 int get_blockid(int i, int j){ 17 i /= 3; 18 j /= 3; 19 return i * 3 + j; 20 } 21 bool ok(int i, int j, int x){ 22 return !row_f[i][x] && !col_f[j][x] && !block_f[get_blockid(i, j)][x]; 23 } 24 void setnum(int i, int j, int x, int f){ 25 row_f[i][x] = f; 26 col_f[j][x] = f; 27 block_f[get_blockid(i, j)][x] = f; 28 } 29 bool dfs(int n){//处理前n个空白格 30 if(n < 0) return true; 31 int r = bk[n].i; 32 int c = bk[n].j; 33 for(int x = 1; x <= 9; ++x){ 34 if(ok(r, c, x)){ 35 setnum(r, c, x, 1); 36 g[r][c] = x; 37 if(dfs(n - 1)) return true; 38 setnum(r , c, x, 0); 39 } 40 } 41 return false; 42 } 43 int main(){ 44 int t, i, j; 45 char c; 46 scanf("%d", &t); 47 while(t--){ 48 bk.clear(); 49 memset(row_f, 0, sizeof(row_f)); 50 memset(col_f, 0, sizeof(col_f)); 51 memset(block_f, 0, sizeof(block_f)); 52 for(i = 0; i < 9; ++i){ 53 for(j = 0 ;j < 9; ++j){ 54 cin >> c; 55 g[i][j] = c - '0'; 56 if(!g[i][j]) 57 bk.push_back(blank(i, j)); 58 else 59 setnum(i, j, g[i][j], 1); 60 } 61 } 62 if(dfs(bk.size()-1)){ 63 for(i = 0; i < 9; ++i){ 64 for(j = 0; j < 9 ; ++j) 65 printf("%c", g[i][j] + '0'); 66 printf(" "); 67 } 68 } 69 } 70 return 0; 71 }