题意：判断摆放过程中是否出现已经出现过的图案，图案可以顺时针旋转90°，180°和水平翻转。
分析：字符串哈希判重
1 #include <cstdio> 2 #include <cstring> 3 4 const int MAXN = 100007; 5 6 char map[52][52]; 7 char temp[52][52]; 8 char temp2[52][52]; 9 bool vis[MAXN]; 10 int N; 11 12 //void show( char (*str)[52] ) 13 //{ 14 // for ( int i = 0; i < N; ++i ) 15 // { 16 // for ( int j = 0; j < N; ++j ) 17 // putchar(str[i][j]); 18 // puts(""); 19 // } 20 //} 21 22 unsigned int BKDRHash( char (*str)[52] ) 23 { 24 unsigned int seed = 31; 25 unsigned int hash = 0; 26 27 for ( int i = 0; i < N; ++i ) 28 for ( int j = 0; j < N; ++j ) 29 hash = hash * seed + str[i][j]; 30 31 return (hash & 0x7FFFFFFF) % MAXN; 32 } 33 34 void Rotate( char (*str)[52], char (*ttemp)[52] ) 35 { 36 for ( int i = 0; i < N; ++i ) 37 for ( int j = 0; j < N; ++j ) 38 ttemp[ j ][ N - 1 - i ] = str[i][j]; 39 // show(str); 40 // show(ttemp); 41 // puts("-------------"); 42 int hash = BKDRHash( ttemp ); 43 // printf("%d\n", hash); 44 vis[hash] = true; 45 return; 46 } 47 48 void Reflact( char (*str)[52] ) 49 { 50 for ( int i = 0; i < N; ++i ) 51 for ( int j = 0; j < N; ++j ) 52 temp[i][N - 1 - j] = str[i][j]; 53 54 int hash = BKDRHash( temp ); 55 vis[hash] = true; 56 return; 57 } 58 59 int main() 60 { 61 int x, y; 62 char ch[3]; 63 int where, who; 64 while ( scanf( "%d", &N ), N ) 65 { 66 bool flag = false; 67 memset( vis, false, sizeof(vis) ); 68 memset( map, '.', sizeof(map) ); 69 70 for ( int i = 0; i < N * 2; ++i ) 71 { 72 scanf("%d%d%s", &x, &y, ch); 73 if ( !flag ) 74 { 75 switch( ch[0] ) 76 { 77 case '+': 78 map[x - 1][y - 1] = '#'; 79 break; 80 81 case '-': 82 map[x - 1][y - 1] = '.'; 83 break; 84 } 85 int hash = BKDRHash( map ); 86 // printf("%d\n", hash); 87 if ( vis[hash] ) 88 { 89 flag = true; 90 where = i + 1; 91 if ( i % 2 ) who = 1; 92 else who = 2; 93 } 94 vis[hash] = true; 95 Rotate( map, temp ); 96 Rotate( temp, temp2 ); 97 Reflact( map ); 98 } 99 } 100 if ( !flag ) puts("Draw"); 101 else printf( "Player %d wins on move %d\n", who, where ); 102 } 103 return 0; 104 }