UVA 10400 Game Show Math

#include <map>
#include <set>
#include <list>
#include <cmath>
#include<cctype>
#include <ctime>
#include <deque>
#include <stack>
#include <queue>
#include <cstdio>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define PI 3.1415926535897932626
using namespace std;
int gcd(int a, int b)
{
return a % b == 0 ? b : gcd(b, a % b);
}
//LRJ把这个题目放在第八章，感觉应该是回溯解决
int src[110];
int tot[110];//存储符号
char tt[4]={'+','-','*','/'};
int flag;
int des,leap;
int result;
int vis[110][65000];
//int tot[110];
void slove(int cur)
{
if (flag)return ;
if (cur==leap-1)
{
if (result==des)
{
flag=1;
for (int i=0;i<leap-1;i++)
{
printf("%d",src[i]);
printf("%c",tt[tot[i]]);
}
printf("%d=%d\n",src[leap-1],des);
return ;
}
else return ;
}
int res=result;
for (int i=0;i<4;i++)
{   if (flag) break;
tot[cur]=i;
if (i==0)
{
if (abs(src[cur+1]+result)>32000 || vis[cur+1][src[cur+1]+result+32000])
continue;
vis[cur+1][src[cur+1]+result+32000]=1;
result+=src[cur+1];
slove(cur+1);
}
else if (i==1)
{
if (abs(result-src[cur+1])>32000 || vis[cur+1][(result-src[cur+1])+32000])  continue;
vis[cur+1][(result-src[cur+1])+32000]=1;
result-=src[cur+1];
slove(cur+1);
}
else if (i==2)
{
if (abs(src[cur+1]*result)>32000 || vis[cur+1][src[cur+1]*result+32000]) continue;
vis[cur+1][src[cur+1]*result+32000]=1;
result*=src[cur+1];
slove(cur+1);
}
else
{
if (src[cur+1]==0 || vis[cur+1][result/src[cur+1]+32000] || abs(result/src[cur+1])>32000) continue;
vis[cur+1][result/src[cur+1]+32000]=1;
result/=src[cur+1];
slove(cur+1);
}
result=res;
}
}
int main()
{
int N;
scanf("%d\n",&N);
while (N--)
{
scanf("%d",&leap);
if (leap==0) break;
for (int i=0;i<leap;i++)
scanf("%d",&src[i]);
scanf("%d",&des);
flag=0;
result=src[0];
memset(vis,0,sizeof(vis));
vis[0][result]=1;
slove(0);
if (!flag) printf("NO EXPRESSION\n");
}
return 0;
}