HDU 5783 Divide the Sequence

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-8;
void File()
{
    freopen("D:\\in.txt","r",stdin);
    freopen("D:\\out.txt","w",stdout);
}
inline int read()
{
    char c = getchar();  while(!isdigit(c)) c = getchar();
    int x = 0;
    while(isdigit(c)) { x = x * 10 + c - ‘0‘; c = getchar(); }
    return x;
}

stack<LL>s;
int n;LL x;

int main()
{
    while(~scanf("%d",&n))
    {
        while(!s.empty()) s.pop();
        for(int i=1;i<=n;i++)
        {
            scanf("%lld",&x);
            if(s.empty()) s.push(x);
            else
            {
                if(x>=0)
                {
                    if(s.top()>=0) s.push(x);
                    else
                    {
                        LL top=s.top(); s.pop();
                        s.push(x+top);
                    }
                }
                else
                {
                    while(1)
                    {
                        LL top=s.top(); s.pop();
                        x=x+top;
                        if(x>=0) break;
                        if(s.empty()) break;
                    }
                    s.push(x);
                }
            }
        }
        printf("%d\n",s.size());
    }
    return 0;
}