Rails UVA - 514 (栈+模拟 难度3)

题目链接

一道模拟+栈的题目
直接遍历判断就好了, 不必全部预处理.
对于每节车厢, 有三种操作:

• 由A直接驶向B
• 由A先驶向C
• 由C直接驶向B
  注意这道题的输入有些独特, 稍加判断

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <stdlib.h>
#include <vector>
#include <queue>
#include <cmath>
#include <stack>
#include <map>
using namespace std;
#define ms(x, n) memset(x,n,sizeof(x));
typedef  long long LL;
const LL maxn = 1010;

int n, m, B[maxn];

int main()
{
   while(cin >> n && n){
       ms(B, 0);
       while(cin >> m && m){
           if(m != 0) B[1] = m;
           else break;

           for(int i = 2; i <= n; i++)
               cin >> B[i];

           int A = 1, i = 1;
           stack<int> C;
           bool flag = true;
           while(i <= n){
               if(A == B[i]) //情况1: 直接A->B
                   A++, i++;
               else if(!C.empty() && C.top()==B[i]) //情况2: C->B
                   i++, C.pop();
               else if(A <= n) //情况3: A->C
                   C.push(A++);
               else {
                   flag = false;
                   break;
               }
           }
           if(flag)
               cout << "Yes" << endl;
           else
               cout << "No" << endl;
       }
       cout << endl;
   }

   return 0;
}