poj3983(牛人啊)
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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
;
}