UVa 387 - A Puzzling Problem

题目链接:http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=109&page=show_problem&problem=323

题目描述：给定几个图形，问能否拼成一个4*4的矩形

分析：这个题虽然放在难回溯里，但因为没有旋转翻转之类的操作，所以不是很难。一行一行的放就行了。

 

  1 #include <cstdio>
  2 #include <cstring>
  3 
  4 const int MAXN = 10;
  5 
  6 struct piece
  7 {
  8     int r, c;
  9     char tu[MAXN][MAXN];
 10 };
 11 
 12 piece P[210];
 13 char map[MAXN][MAXN];
 14 bool vis[210];
 15 int n;
 16 
 17 void putdown( int cur, int x, int y )
 18 {
 19     for ( int i = 0; i < P[cur].r; ++i )
 20         for ( int j = 0; j < P[cur].c; ++j )
 21         {
 22             if ( P[cur].tu[i][j] - '0' )
 23                 map[x + i][y + j] = cur + 1 + '0';
 24         }
 25     return;
 26 }
 27 
 28 void clear( int cur, int x, int y )
 29 {
 30     for ( int i = 0; i < P[cur].r; ++i )
 31         for ( int j = 0; j < P[cur].c; ++j )
 32         {
 33             if ( P[cur].tu[i][j] - '0' )
 34                 map[x + i][y + j] = '*';
 35         }
 36     return;
 37 }
 38 
 39 bool check( int cur, int x, int y )
 40 {
 41     for ( int i = 0; i < P[cur].r; ++i )
 42         for ( int j = 0; j < P[cur].c; ++j )
 43         {
 44             if ( P[cur].tu[i][j] - '0' )
 45             {
 46                 if ( map[x + i][y + j] != '*' )
 47                     return false;
 48 
 49                 if ( x + i >= 4 || y + j >= 4 )
 50                     return false;
 51             }
 52         }
 53     return true;
 54 }
 55 
 56 void Print()
 57 {
 58     for ( int i = 0; i < 4; ++i )
 59     {
 60         for ( int j = 0; j < 4; ++j )
 61             putchar( map[i][j] );
 62         putchar('\n');
 63     }
 64     return;
 65 }
 66 
 67 bool DFS( int cur )
 68 {
 69     if ( cur == n )
 70     {
 71         for ( int i = 0; i < 4; ++i )
 72             for ( int j = 0; j < 4; ++j )
 73                 if ( map[i][j] == '*' ) return false;
 74         return true;
 75     }
 76 
 77     for ( int x = 0; x < 4; ++x )
 78         for ( int y = 0; y < 4; ++y )
 79         {
 80             for ( int i = 0; i < n; ++i )
 81                 if ( !vis[i] )
 82                 {
 83 //                    printf("%d %d %d\n", i, x, y);
 84 //                    Print();
 85                     vis[i] = true;
 86                     if ( check( cur, x, y ) )
 87                     {
 88                         putdown( cur, x, y );
 89                         if ( DFS( cur + 1 ) ) return true;
 90                         clear( cur, x, y );
 91                     }
 92                     vis[i] = false;
 93                 }
 94         }
 95 
 96     return false;
 97 }
 98 
 99 int main()
100 {
101 //    freopen( "s.out", "w", stdout );
102     bool notfirst = false;
103     while ( scanf( "%d", &n ), n )
104     {
105         for ( int i = 0; i < n; ++i )
106         {
107             scanf( "%d%d", &P[i].r, &P[i].c );
108             for ( int j = 0; j < P[i].r; ++j )
109                 scanf( "%s", P[i].tu[j] );
110         }
111 
112         memset( vis, false, sizeof(vis) );
113         memset( map, '*', sizeof(map) );
114 
115         if ( notfirst ) puts("");
116 
117         if ( DFS( 0 ) ) Print();
118         else puts("No solution possible");
119         notfirst = true;
120     }
121     return 0;
122 }
posted @ 2012-11-06 21:25  冰鸮  阅读(177)  评论(0)  编辑  收藏  举报