アルゴリズム道中記~20240407~

A Penalty Kick

A - Penalty Kick

#include <bits/stdc++.h>
#define print(x) cout << x << endl;
#define rep(i, s, n) for (long long i = s; i < (long long)(n); i++)
using namespace std;
using ll = long long;

int main() {
  ll N;
  cin >> N;
  rep (i, 1, N+1)
  {
    if (i % 3) cout << "o";
    else cout << "x";
  }
  cout << endl;
}

B Farthest Point

B - Farthest Point

#include <bits/stdc++.h>
#define print(x) cout << x << endl;
#define rep(i, s, n) for (long long i = s; i < (long long)(n); i++)
using namespace std;
using ll = long long;

int main() {
  ll N;
  cin >> N;
  vector<pair<ll, ll>> pos(N);
  rep (i, 0, N)
    cin >> pos[i].first >> pos[i].second;
  rep (i, 0, N)
  {
    ll maxDistance = 0, maxIndex = 0;
    rep (k, 0, N)
    {
      ll dx = pos[i].first - pos[k].first;
      ll dy = pos[i].second - pos[k].second;
      ll dis = dx*dx + dy*dy;
      if (maxDistance < dis)
      {
        maxDistance = dis;
        maxIndex = k+1;
      }
      else if (maxDistance == dis)
      {
        if (maxIndex > k+1)
          maxIndex = k+1;
      }
    }
    print(maxIndex);
  }
}

C Colorful Beans

C - Colorful Beans

#include <bits/stdc++.h>
#define print(x) cout << x << endl;
#define rep(i, s, n) for (long long i = s; i < (long long)(n); i++)
using namespace std;
using ll = long long;

int main() {
  ll N;
  cin >> N;
  map<ll, ll> m;
  rep (i, 0, N)
  {
    ll A, C;
    cin >> A >> C;
    if (m.count(C))
      m[C] = min(m[C], A);
    else
      m[C] = A;
  }
  ll ans = 0;
  for (const auto &[k, v] : m)
    ans = max(ans, m[k]);
  print(ans);
}

mapのkeyを取得する方法を知らず、少々戸惑いました。

for (const auto &[k, v] : m)

と記述することで、keyと値を取り出すことができました。

参考

C++ でマップからすべてのキーを取得する