UVa514

Posted on In , Views:

題目:
https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=7&page=show_problem&problem=455

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
#include <bits/stdc++.h>
using namespace std;
int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int n=0; // the sequence length
    int arr[1005] = {}; // to store the input sequence
    while(cin >> n && n != 0){
        while(cin >> arr[1] && arr[1] != 0){
            for(int i=2; i<=n; ++i) cin >> arr[i]; // arr[1] ~ arr[n] is the sequence we want to make
            stack<int> s;
            int k = 1; // is used to record the relation
            for(int j=1; j<=n; ++j){ // start pushing the stack with 1, 2, ..., n sequence
                s.push(j);
                while(!s.empty() && s.top() == arr[k]){ 
                // if stack top == arr[k], we pop the top and ++k, means k already moved to station B
                    s.pop();
                    ++k;
                }
            }
            cout << (s.empty() ? "Yes" : "No") << '\n';
        }
        cout << '\n';
    }
    return 0;
}