火车进站

 1 #include <iostream>
 2 #include <stack>
 3 #include <stdio.h>
 4 using namespace std;
 5 const int MAXN = 1000 + 10;
 6 
 7 int n, target[MAXN];
 8 
 9 int main(){
10     while(cin >> n){
11         stack<int>  s;
12         int A = 1, B = 1;
13         for(int i = 1; i <= n; i++){
14             cin >> target[i];
15         }
16         int ok = 1; 
17         while(B <= n){
18             if(A == target[B]){
19                 A++;
20                 B++;
21             }
22             else if(!s.empty() && s.top() == target[B]){
23                 s.pop();
24                 B++;
25             }
26             else if(A < n){
27                 s.push(A++);
28             }
29             else{
30                 ok = 0; 
31                 break;
32             }
33         }
34         printf("%s
",ok ? "Yes" : "No");
35     }
36     return 0;
37 }