poj 1363：火車合法的出棧次序——合法的出棧次序

#include <stdio.h>

#include <stack>
#include <queue>

bool check_is_valid_order(std::queue<int> &order){
	std::stack<int> S;//臨時棧
	int n = order.size();//獲得測試隊列，即出棧次序的長度
	for (int i = 1; i <= n; i++){
		S.push(i);//將1,2,3,4,5,6,7,8......入棧
		while(!S.empty() && order.front() == S.top()){//如果棧S不爲空，且 測試隊列的頭 == 棧頂
			S.pop();//棧頂和隊列頭同時彈出
			order.pop();
		}
	}
	if (!S.empty()){//如果棧S不爲空，說明測試隊列的次序 不滿足合法出棧次序
		return false;
	}
	return true;
}

int main(){
	int n;
	int train;
	scanf("%d", &n);
	while(n){
		scanf("%d", &train);
		while (train){
			std::queue<int> order;
			order.push(train);
			for (int i = 1; i < n; i++){
				scanf("%d", &train);
				order.push(train);
			}
			if (check_is_valid_order(order)){
				printf("Yes\n");
			}
			else{
				printf("No\n");
			}
			scanf("%d", &train);
		}
		printf("\n");
		scanf("%d", &n);
	}
	return 0;
}