Submission #1176859

---

Source Code Expand

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define MP make_pair
#define PB push_back
#define MOD 1000000007
#define INF (1LL<<30)
#define LLINF (1LL<<60)
#define PI 3.14159265359
#define EPS 1e-12
//#define int ll

string s[105];
signed main(void)
{
  stack<int> st;
  int n;
  cin >> n;
  REP(i, n) cin >> s[i];
  REP(i, n) {
    if(s[i] == "A") {
      if(st.empty() || st.top() == 1) st.push(1);
      else {
        cout << "NO" << endl;
        return 0;
      }
    } else {
      if(st.size() && st.top() == 1) {
        st.pop();
      } else {
        cout << "NO" << endl;
        return 0;
      }
    }
  }
  if(st.size()) cout << "NO" << endl;
  else cout << "YES" << endl;
  return 0;
}

Submission Info

Judge Result