gfoj1645 盘子序列

题目：http://www.gdfzoj.com/oj/contest/462/problems/1

 

 

 

#include <cstdio>
#include <algorithm>
#include <cstring>
#include <stack>

using namespace std;

const int maxS=100000;
int a[maxS+5],c[maxS+5];
stack<int> s;
int n;

int main()
{
	int i,j,i1,t,maxc;
	
	freopen("a.txt","r",stdin);
	while (scanf("%d",&n)!=EOF)
	{
		t=0;	maxc=0;
		memset(a,0,sizeof(a));
		memset(c,0,sizeof(c));
		while (!s.empty())
			s.pop();
			
		for (i=1;i<=n;i++)
		{
			scanf("%d",&a[i]);
			c[i]=a[i];
		}
		sort(a+1,a+n+1);
		for (i=1;a[i]<c[1];i++)
			s.push(a[i]);
		maxc=i;		//maxc在a的下标 
		for (i=2;i<=n;i++)
		{
			if (c[i]>a[maxc])
			{
				i1=lower_bound(a+1,a+n+1,c[i])-a;
				for (j=maxc+1;j<i1;j++)
					s.push(a[j]);
				maxc=i1;
			}
			else
				if (c[i]==s.top())
					s.pop();
				else
				{
					t=1;	printf("J\n");
					break;
				}
		}
		if (t==0)
			printf("Y\n");
	}
	
	
	
	return 0;
}