{HDU}{4193}{Nonnegative Partial Sums}

对数组进行预处理，由于是连续的可以在O(1)的时间进行判定查询，WA了N次。

#include <iostream>
#include <string>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <memory>
#include <cmath>
#include <bitset>
#include <queue>
#include <vector>
#include <stack>
using namespace std;

const int MAXN = 550;

#define CLR(x,y) memset(x,y,sizeof(x))
#define MIN(m,v) (m)<(v)?(m):(v)
#define MAX(m,v) (m)>(v)?(m):(v)
#define ABS(x) ((x)>0?(x):-(x))
#define rep(i,x,y) for(i=x;i<y;++i)
int minval[1200000];
int minvalf[1200000];
int s[1200000];
int b;

int work()
{
	int n;
	int i,j,tmp,k,h,val,p;
	while( scanf("%d",&n) && n ) {
		b = 0;
		rep(i,0,n){
			scanf("%d",&s[i]);
			s[i] += b;
			b = s[i];
		}
		val = (1<<30);
		for( i = n-1; i >= 0; --i) {
			if(s[i] < val){
				val = s[i];
			}
			minval[i] = val;
		}
		val = (1<<30);
		rep(i,0,n) {
			if( s[i] < val ) {
				val = s[i];
			}
			minvalf[i] = val;
		}
		int ans = 0;
		minval[n] = (1<<30);
		rep(i,0,n){
			val = minval[i+1];
			if( val - s[i] >= 0 && s[n-1]-s[i]+minvalf[i] >= 0 ) 
				++ans;
		}
		printf("%d\n",ans);
	}
	return 0;
}
int main()
{
	work();
	return 0;
}