uva 10400 - Game Show Math

#include <cstdio>
#include <cstring>
#include <cctype>
#include <cstdlib>
#include <queue>
#include <stack>
#include <cmath>
#include <string>
#include <iostream>
#include <map>
#include <algorithm>
using namespace std;
#define maxn 100 + 10
#define INF 2100000000
#define ll long long
bool ok;
int ans;
int fis[maxn];
char sy[4] = {'+', '-', '*', '/'};
bool vis[maxn][64010];
int n, a[maxn], s[maxn];
bool judgs(int m, int cur)
{
if(m >= -32000 && m <= 32000 && !vis[cur][m]) return true;
return false;
}
void dfs(int cur, int sum)
{
if(ok) return;
if(cur == n)
{
if(sum == ans) {
ok = true;
for(int i = 1; i < n; ++i)
fis[i] = s[i];
}
return;
}
s[cur] = 0;
if(judgs(sum+a[cur], cur+1))
dfs(cur+1, sum+a[cur]), vis[cur+1][sum+a[cur]] = true;
s[cur] = 1;
if(judgs(sum-a[cur], cur+1))
dfs(cur+1, sum-a[cur]), vis[cur+1][sum-a[cur]] = true;
s[cur] = 2;
if(judgs(sum*a[cur], cur+1))
dfs(cur+1, sum*a[cur]), vis[cur+1][sum*a[cur]] = true;
s[cur] = 3;
if(a[cur]!=0 && sum%a[cur] == 0 && judgs(sum/a[cur], cur+1))
dfs(cur+1, sum/a[cur]);
return;
}
int main()
{
int t;
scanf("%d", &t);
while(t--)
{
scanf("%d", &n);
for(int i = 0; i < n; ++i)
scanf("%d", &a[i]);
scanf("%d", &ans);
ok = false;
memset(vis, false, sizeof(vis));
dfs(1, a[0]);
if(ok) {
printf("%d", a[0]);
for(int i = 1; i < n; ++i)
printf("%c%d", sy[fis[i]], a[i]);
printf("=%d\n", ans);
}
else puts("NO EXPRESSION");
}
return 0;
}