//每组数据包含一行字符串，即24点游戏的表达式树的先序遍历序列，输入‘#’代表空树
//对于每组数据，输出一行。如果不能得到24，输出“NO”。如果能得到24，按样例输出。
/*例如
+ + + 6 # # 6 # # 6 # # 6 # #
- - * 6 # # 6 # # 6 # # 6 # #
* * 1 # # 2 # # * 1 # # 2 # #
(((6+6)+6)+6)=24
(((6*6)-6)-6)=24
NO*/
//源码
#include <iostream>
#include <cctype>
#include <cstring>
#include <cstdio>
#include <string>
#include <stdlib.h>
#include <iomanip>
using namespace std;
 
typedef struct BiTNOde
{
    char data[4];
    struct BiTNOde *lchild,*rchild;
} BiTNOde,*BiTree;
 
void CreateBiTree(BiTree &t)
{
    char ch[4];
    if(!(cin>>ch))
        exit(0);
    if(ch[0]=='#')
        t=NULL;
    else
    {
        t=new BiTNOde;
        strcpy(t->data,ch);
        CreateBiTree(t->lchild);
        CreateBiTree(t->rchild);
    }
}
void DestoryBi(BiTree &t)
{
    if(t)
    {
        DestoryBi(t->lchild);
        DestoryBi(t->rchild);
        delete t;
    }
}
 
void PrintTraverse(BiTree t)
{
    if(t)
    {
        if(t->lchild)
            cout<<'(';
        PrintTraverse(t->lchild);
        cout<<t->data;
        PrintTraverse(t->rchild);
        if(t->rchild)
            cout<<')';
    }
 
}
 
double Myatoi(char *s)//(用库给的不行，用自己的试试)
{
    double sum=0;
    for(int i=0;s[i]!='\0';i++)
        sum=sum*10+s[i]-'0';
    return sum;
}
 
double Answer(BiTree t)
{
    if(t)
    {
        if(!t->lchild) return Myatoi(t->data);
        double x=Answer(t->lchild);
        double y=Answer(t->rchild);
 
        switch (t->data[0])
        {
            case'+':cout<<"x+y="<<x+y<<endl;return x+y;
            case'-':cout<<"x-y="<<x-y<<endl;return x-y;
            case'*':cout<<"x*y="<<x*y<<endl;return x*y;
            case'/':cout<<"x/y="<<x/y<<endl;return x/y;
        }
    }
}
 
int main()
{
    while(1)
    {
        BiTree t;
        CreateBiTree(t);
        if((int)Answer(t)==24){
        PrintTraverse(t);
        cout<<"=24"<<endl;
        }
        else cout<<"NO"<<endl;
        DestoryBi(t);
    }
    return 0;
}
//  / 8 # # - 3 # # / 8 # # 3 # #   （这组数据过不了）
//  - * 5 # # 5 # # / 8 # # 8 # #

对了，case后面的输出是我用来测试每一次递归的数值的

。。。case被谷歌给翻译了

那个数据在double下是24，在int下是23，加了个0.00001就好了