[UVa]514 - Rails

[UVa]514.cpp

#include<iostream>
#include<cstdio>
#include<stack>
using namespace std ;
const int maxn = 10000 ;
int main(){
    int n , k , num[maxn];
    while(scanf("%d" , &n) == 1 && n){
        num[0] = 0 ;
        for(;;){
            for(int i = 1 ; i <= n ; i++){
                scanf("%d" , &num[i]);
                if(!num[i])break ;
            }
            if(!num[1])break ;

            int cur = n , out = n;
            stack<int> sk ;

            while(out >= 0){
                if(num[out] == cur){out-- ; cur-- ;}
                else if(!sk.empty() && sk.top() == cur){sk.pop() ; cur-- ;}
                else sk.push(num[out--]) ;
            }

            if(sk.empty())puts("Yes");
            else puts("No");
        }
	printf("\n") ;
    }
}