HDU 3647 Tetris （暴力DFS）
题意：给你十个俄罗斯方块，问你能否拼成指定长宽的矩形，方块下落的顺序是严格确定的，后下落的方块不能落在先下落的方块之下。
每个俄罗斯方块都是由更小的小方格拼成的，
可以用一个一维数组来记录每一列已经摞上了多少个小方格。DFS遵循底部放满原则，如果可以恰好和已存在的方块实现无缝拼接才往上放，否则回溯。
#include <iostream>
#include <cstring>
using namespace std;
char tet[20]; //记录方块的下降次序
int box[45]; //把方块分成小格子，记录每列有多个小格子
int m, n;
bool DFS( int cur )
{
if ( cur == 10 ) return true;
switch( tet[cur] )
{
case 'I' :
for ( int i = 0; i < n; i++ )
{
if ( box[i] + 4 <= m ) //判断能不能竖着放
{
box[i] += 4;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 4;
}
if ( i + 3 < n && box[i] == box[i + 1] && box[i + 1] == box[i + 2] && box[i + 2] == box[i + 3] && box[i] + 1 <= m ) //能不能横着放
{
for ( int j = i; j < i + 4; j++ ) ++box[j];
if ( DFS( cur + 1 ) ) return true;
for ( int j = i; j < i + 4; j++ ) --box[j];
}
}
break;
case 'O':
for ( int i = 0; i < n; i++ )
{
if ( i + 1 < n && box[i] == box[i + 1] && box[i] + 2 <= m )
{
box[i] += 2;
box[i + 1] += 2;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 2;
box[i + 1] -= 2;
}
}
break;
case 'L' :
for ( int i = 0; i < n; i++ )
{
if ( i + 1 < n && box[i] + 3 <= m && box[i] == box[i + 1] ) //正着放L
{
box[i] += 3;
box[i + 1] += 1;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 3;
box[i + 1] -= 1;
}
if (i + 2 < n && box[i] + 1 == box[i + 1] && box[i + 1] == box[i + 2] && box[i] + 2 <= m && box[i + 1] + 1 <= m ) //顺时针旋转90°
{
box[i] += 2;
box[i + 1] += 1;
box[i + 2] += 1;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 2;
box[i + 1] -= 1;
box[i + 2] -= 1;
}
if (i + 1 < n && box[i] + 1 <= m && box[i + 1] + 3 <= m && box[i + 1] + 2 == box[i] ) //顺时针旋转180°
{
box[i] += 1;
box[i + 1] += 3;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 1;
box[i + 1] -= 3;
}
if (i + 2 < n && box[i] == box[i + 1] && box[i + 1] == box[i + 2] && box[i + 2] + 2 <= m ) //顺时针旋转270°
{
box[i] += 1;
box[i + 1] += 1;
box[i + 2] += 2;
if ( DFS(cur + 1) ) return true;
box[i] -= 1;
box[i + 1] -= 1;
box[i + 2] -= 2;
}
}
break;
case 'J' :
for ( int i = 0; i < n; i++ )
{
if (i + 1 < n && box[i] == box[i + 1] && box[i + 1] + 3 <= m ) //0
{
box[i] += 1;
box[i + 1] += 3;
if ( DFS(cur + 1) ) return true;
box[i] -= 1;
box[i + 1] -= 3;
}
if (i + 2 < n && box[i] == box[i + 1] && box[i + 1] == box[i + 2] && box[i] + 2 <= m) //90
{
box[i] += 2;
box[i + 1] += 1;
box[i + 2] += 1;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 2;
box[i + 1] -= 1;
box[i + 2] -= 1;
}
if (i + 1 < n && box[i] + 2 == box[i + 1] && box[i] + 3 <= m && box[i + 1] + 1 <= m ) //180
{
box[i] += 3;
box[i + 1] += 1;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 3;
box[i + 1] -= 1;
}
if (i + 2 < n && box[i] == box[i + 1] && box[i + 2] + 1 == box[i + 1] && box[i] + 1 <= m && box[i + 2] + 2 <= m) //270
{
box[i] += 1;
box[i + 1] += 1;
box[i + 2] += 2;
if ( DFS(cur + 1) ) return true;
box[i] -= 1;
box[i + 1] -= 1;
box[i + 2] -= 2;
}
}
break;
case 'Z' :
for ( int i = 0; i < n; i++ )
{
if (i + 2 < n && box[i + 2] == box[i + 1] && box[i + 1] + 1 == box[i] && box[i] + 1 <= m && box[i + 1] + 2 <= m ) //0
{
box[i] += 1;
box[i + 1] += 2;
box[i + 2] += 1;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 1;
box[i + 1] -= 2;
box[i + 2] -= 1;
}
if (i + 1 < n && box[i] + 1 == box[i + 1] && box[i] + 2 <= m && box[i + 1] + 2 <= m) //90
{
box[i] += 2;
box[i + 1] += 2;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 2;
box[i + 1] -= 2;
}
}
break;
case 'S' :
for ( int i = 0; i < n; i++ )
{
if (i + 2 < n && box[i] == box[i + 1] && box[i + 1] + 1 == box[i + 2] && box[i + 1] + 2 <= m && box[i + 2] + 1 <= m ) //0
{
box[i] += 1;
box[i + 1] += 2;
box[i + 2] += 1;
if ( DFS(cur + 1) ) return true;
box[i] -= 1;
box[i + 1] -= 2;
box[i + 2] -= 1;
}
if (i + 1 < n && box[i + 1] + 1 == box[i] && box[i] + 2 <= m && box[i + 1] + 2 <= m ) //90
{
box[i] += 2;
box[i + 1] += 2;
if ( DFS(cur + 1) ) return true;
box[i] -= 2;
box[i + 1] -= 2;
}
}
break;
case 'T' :
for ( int i = 0; i < n; i++ )
{
if ( i + 2 < n && box[i] == box[i + 1] && box[i + 1] == box[i + 2] && box[i + 1] + 2 <= m ) //0
{
box[i] += 1;
box[i + 1] += 2;
box[i + 2] += 1;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 1;
box[i + 1] -= 2;
box[i + 2] -= 1;
}
if ( i + 1 < n && box[i] + 1 == box[i + 1] && box[i] + 3 <= m ) //90
{
box[i] += 3;
box[i + 1] += 1;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 3;
box[i + 1] -= 1;
}
if ( i + 2 < n && box[i] == box[i + 2] && box[i + 1] + 1 == box[i] && box[i + 1] + 2 <= m ) //180
{
box[i] += 1;
box[i + 1] += 2;
box[i + 2] += 1;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 1;
box[i + 1] -= 2;
box[i + 2] -= 1;
}
if ( i + 1 < n && box[i + 1] + 1 == box[i] && box[i + 1] + 3 <= m ) //270
{
box[i] += 1;
box[i + 1] += 3;
if ( DFS( cur + 1 ) ) return true;
box[i] -= 1;
box[i + 1] -= 3;
}
}
break;
}
return false;
}
int main()
{
while(cin>>n>>m&&n||m)
{
for(int i=0; i<10; i++)
cin>>tet[i];
memset(box, 0, sizeof(box));
if(DFS(0))
cout<<"Yes"<<endl;
else
cout<<"No"<<endl;
}
return 0;
}
版权声明：本文为博主原创文章，未经博主允许不得转载。
