uva 10400 Game Show Math

#include <cstdio>
#include <cmath>
#include <cstring>
#include <iostream>
using namespace std;

int flag,n,b[101],ans,a[101],vis[100][64001];

void dfs(int sum,int deep)
{
    if (deep > n && sum == ans) 
    {
        flag=1; 
        return;
    }
    if (flag || deep > n || abs(sum) > 32000)
        return;
    for (int i = 1; i <= 4; i++)
    {
        b[deep-1] = i;
        int s = 32001;
        if (i == 1) 
            s = sum + a[deep];
        if (i == 2) 
            s = sum - a[deep];
        if (i == 3)
            s = sum * a[deep];
        if (i == 4 && (sum % a[deep] == 0)) 
            s = sum / a[deep];
        if (abs(s) <=32000 && vis[deep-1][s] == 0)
        {
            vis[deep-1][s]=1;
            dfs(s,deep+1);
        }
        if (flag)
            return;
    }
}
int main()
{ 
    int t;
    scanf("%d",&t);
    while (t--)
    {
        scanf("%d",&n);
        for (int i = 1; i <= n; i++)
            scanf("%d",&a[i]);
        scanf("%d",&ans);
        flag=0;
        memset(vis,0,sizeof(vis));
        dfs(a[1],2);
        if (flag)
        {
            for (int i =1 ; i < n; i++)
            {
                printf("%d",a[i]);
                if (b[i] == 1)
                    printf("+");
                if (b[i] == 2) 
                    printf("-");
                if (b[i] == 3)
                    printf("*");
                if (b[i] == 4)
                    printf("/");
            }
            printf("%d=%d\n",a
,ans);
        }
        else
            printf("NO EXPRESSION\n");
    }
    return 0;
}