spoj 95

栈应用 ...... 水题

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>

using namespace std;

int a[1010], b[1010];

int main()
{
    int n;
    while(scanf("%d",&n) == 1 && n)
    {
        for(int i = 0; i < n; i++)  scanf("%d",&a[i]);
        int top = 0, ff = 0, bb = 1;
        while(true)
        {
            while(top && b[top-1] == bb)  top--, bb++;
            if(a[ff] == bb) ff++, bb++;
            else b[top++] = a[ff++];
            if(ff == n+1) break;
        }
        if(bb == n+1) puts("yes");
        else puts("no");
    }
    return 0;
}