poj 2372 D++ Again

#include<cstdio>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdlib>
#include<iomanip>
#include<string>
#include<vector>
#include<map>
#include<string>
#include<iostream>
#include<algorithm>
using namespace std;
#define INF 0x3f3f3f3f
typedef long long ll;
#define Max(a,b) (a>b)?a:b
#define lowbit(x) x&(-x)
int main()
{
    map<char,bool>vis;
    vis[‘1‘]=1;
    vis[‘2‘]=1;
    vis[‘3‘]=1;
    vis[‘4‘]=1;
    vis[‘5‘]=1;
    vis[‘6‘]=1;
    vis[‘7‘]=1;
    vis[‘8‘]=1;
    vis[‘9‘]=1;
    vis[‘0‘]=1;
    vis[‘+‘]=1;
    vis[‘-‘]=1;
    vis[‘*‘]=1;
    vis[‘/‘]=1;
    vis[‘\n‘]=1;
    vis[‘=‘]=1;
    char t,last=0;
    int sum=0,flag=0,ans=1;
    while(~scanf("%c",&t))
    {
        if(flag==1||ans==0)
        {
                if(t==‘)‘)
                {
                    if(last==‘*‘)
                    {
                        flag=0;
                    }
                }
                last=t;
                continue;
        }
        if(t==‘*‘&&last==‘(‘)
            {
                flag=1,sum--;
                continue;
            }
            else if(sum==0&&t==‘)‘&&last==‘*‘)
                ans=0;
        if(sum<0)
        {
            ans=0;
            continue;
        }
        else if(sum>0)
        {
            if(t==‘)‘)
            {
                sum--;
            }

            else if(t==‘(‘)
                    sum++;
            else if(vis[t]==0)
                ans=0;
            last=t;
        }
        else
        {
            if(t==‘(‘)
               {
                   sum++;
               }
            else if(t==‘)‘)
                sum--;
            last=t;
        }
    }
    if(sum||flag||ans==0)
        puts("NO");
    else
        puts("YES");
}