Submission #554500

#	Time	Username	Problem	Language	Result	Execution time	Memory
554500		ollel	Three Friends (BOI14_friends)	C++14	0 / 100	91 ms	7160 KiB

friends

using namespace std;
#include <bits/stdc++.h>

#define rep(i,a,b) for(int i = a; i < b; i++)
#define pb push_back

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<bool> vb;
typedef long long ll;

int n,m;
string u;

int main() {
  cin >> n; m = (n - 1) / 2;
  cin >> u;

  int numberEqual = 0;
  vi cands;

  rep(i,1,m+1) if (u[i] == u[i + m]) numberEqual++;

  if (numberEqual == m) cands.pb(0);

  rep(skip, 1, m) {
    if (u[skip] == u[skip + m]) numberEqual--;
    if (u[skip - 1] == u[skip + m]) numberEqual++;
    if (numberEqual == m) cands.pb(skip);
  }
  numberEqual = 0;
  rep(i,0,m) if (u[i] == u[i + m + 1]) numberEqual++;
  if (numberEqual == m) cands.pb(m);
  rep(skip, m + 1, n) {
    if (u[skip] == u[skip - m - 1]) numberEqual--;
    if (u[skip - 1] == u[skip - m - 1]) numberEqual++;
    if (numberEqual == m) cands.pb(skip);
  }

  if (cands.size() == 0) {
    cout << "NOT POSSIBLE\n";
  }
  else if (cands.size() > 1) {
    cout << "NOT UNIQUE\n";
  }
  else {
    int ans = cands[0];

    vector<char> k;
    int i = -1;
    while (k.size() < m) {
      i++;
      if (i == ans) continue;
      k.pb(u[i]);
    }
    rep(i,0,m) cout << k[i];
    cout << endl;
  }
}

Compilation message (stderr)

friends.cpp: In function 'int main()':
friends.cpp:51:21: warning: comparison of integer expressions of different signedness: 'std::vector<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   51 |     while (k.size() < m) {
      |            ~~~~~~~~~^~~

• Subtask 1: 0 / 35
• Subtask 2: 0 / 65