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// POJ 3983 第二届顶嵌杯决赛A题 计算4个数等于24 // 搜索 数据较小，不用剪枝就过了
// 利用类似层叠那样，每运算一次，就合并两个数，所以少一个数，每次计算的值都保存在curVal中
// 注意浮点数1/3 *3 会等于1
// 格式化输出时用到sprintf，挺不错的
#include < stdio.h >
#include < string .h >
#include < math.h >
#define bool int
int option[ 5 ];
int order[ 5 ];
float number[ 5 ];
float curVal[ 4 ][ 5 ];
// 输出时用到的临时变量
char outputStr[ 15 ];
char outputStr2[ 15 ];
char tempStr[ 15 ];
char tempStr2[ 15 ];
bool bfs( int k)
{
int m;
if (k == 3 )
{
if (fabs( 24.0 - curVal[ 3 ][ 0 ]) == 0 )
return 1 ;
else
return 0 ;
}
else
{
int i,j;
for (i = 0 ;i < 3 - k;i ++ )
{
for (j = 0 ;j < 4 ;j ++ )
{
switch (j)
{
case 0 :
curVal[k + 1 ][i] = curVal[k][i] + curVal[k][i + 1 ];
break ;
case 1 :
curVal[k + 1 ][i] = curVal[k][i] - curVal[k][i + 1 ];
break ;
case 2 :
curVal[k + 1 ][i] = curVal[k][i] * curVal[k][i + 1 ];
break ;
case 3 :
curVal[k + 1 ][i] = curVal[k][i] / curVal[k][i + 1 ];
break ;
}
for (m = 0 ;m < i;m ++ )
curVal[k + 1 ][m] = curVal[k][m];
for (m = i + 1 ;m < 3 - k;m ++ )
curVal[k + 1 ][m] = curVal[k][m + 1 ];
option[k] = j;
order[k] = i;
if (bfs(k + 1 ))
return 1 ;
}
}
}
return 0 ;
}
void OutPut(){
if (order[ 1 ] >= order[ 0 ])
order[ 1 ] ++ ;
order[ 2 ] = 3 - order[ 0 ] - order[ 1 ];
char op[ 4 ] = { ' + ' , ' - ' , ' * ' , ' / ' };
sprintf(outputStr, " (%d%c%d) " ,( int )number[order[ 0 ]],op[ option[ 0 ] ],( int )number[order[ 0 ] + 1 ]);
strcpy(tempStr,outputStr);
if (abs(order[ 0 ] - order[ 1 ]) == 2 )
{
sprintf(outputStr2, " (%d%c%d) " ,( int )number[order[ 1 ]],op[ option[ 1 ] ],( int )number[order[ 1 ] + 1 ]);
strcpy(tempStr2,outputStr2);
if (order[ 0 ] < order[ 1 ])
sprintf(outputStr, " %.*s%c%.*s " , sizeof (tempStr),tempStr,op[ option[ 2 ] ], sizeof (tempStr2),tempStr2);
else
sprintf(outputStr, " %.*s%c%.*s " , sizeof (tempStr2),tempStr2,op[ option[ 2 ] ], sizeof (tempStr),tempStr);
} else
{
if (order[ 0 ] < order[ 1 ])
sprintf(outputStr, " (%.*s%c%d) " , sizeof (tempStr),tempStr,op[ option[ 1 ] ],( int )number[order[ 1 ] + 1 ]);
else
sprintf(outputStr, " (%d%c%.*s) " ,( int )number[order[ 1 ]],op[ option[ 1 ] ], sizeof (tempStr),tempStr);
strcpy(tempStr,outputStr);
if (order[ 2 ] == 2 )
sprintf(outputStr, " %.*s%c%d " , sizeof (tempStr),tempStr,op[ option[ 2 ] ],( int )number[order[ 2 ] + 1 ]);
else
sprintf(outputStr, " %d%c%.*s " ,( int )number[order[ 2 ]],op[ option[ 2 ] ], sizeof (tempStr),tempStr); }
printf( " %s\n " ,outputStr);
}
int main()
{
int i;
for (i = 0 ;i < 4 ;i ++ )
{
scanf( " %f " , & number[i]);
curVal[ 0 ][i] = number[i];
}
bfs( 0 );
OutPut();
return 0 ;
}
转载于:https://my.oschina.net/garyun/blog/602886