zoj 1259 Rails

#include<iostream>#include<stack>using namespace std;int main(){int n,i,count;int target[1000];stack<int> sk;while(cin>>n&&n!=0){while(cin>>target[0]&&target[0]){for(i=1;i<n;i++)cin>>target[i];count=1;i=0; while(i<n){if(count==target[i]){count++;i++;}else{if(!sk.empty()&&sk.top()==target[i]){sk.pop();i++;}else{if(count<=n)sk.push(count++);elsebreak;}}}if(i==n)cout<<"Yes"<<endl;elsecout<<"No"<<endl;while(!sk.empty())sk.pop();}cout<<endl;}return 0;}