Submission #57543

#	Time	Username	Problem	Language	Result	Execution time	Memory
57543		Autoratch	Three Friends (BOI14_friends)	C++14	0 / 100	30 ms	12164 KiB

friends

#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define MOD 1e9 + 7

int n,a[26];
string s,ans = "-";

bool solve(string p,string t)
{
    string tmp;
    tmp = t.substr(1,t.length()-1);
    if(p==tmp){ ans = p; return true; }
    tmp = t.substr(0,t.length()-1);
    if(p==tmp){ ans = p; return true; }
    int lp = 0,lt = 0,l = 0;
    while(true)
    {
        if(p[lp]==t[lt]) l++;
        else break;
        lp++; lt++;
        if(lp>=p.length() or lt>=t.length()) break;
    }
    int rp = p.length()-1,rt = t.length()-1,r = 0;
    while(true)
    {
        if(p[rp]==t[rt]) r++;
        else break;
        rp--; rt--;
        if(rp<0 or rt<0) break;
    }
    if(l+r>=p.length()){ ans = p; return true; }
    else return false;
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);

    cin >> n >> s;

    if(n%2==0){ cout << "NOT POSSIBLE"; return 0; }

    for(int i = 0;i < n;i++) a[s[i]-'A']++;

    int cnt = 0;

    for(int i = 0;i < 26;i++) if(a[i]%2==1){ cnt++; if(cnt>1){ cout << "NOT POSSIBLE"; return 0; }}

    string a = s.substr(0,n/2);
    string b = a+s[n/2];
    string c = s.substr(n/2+1,n/2);
    string d = s[n/2]+c;
    bool x = solve(a,d),y = solve(c,b);

    if(x and y and x!=y){ cout << "NOT UNIQUE"; return 0; }
    else if(ans=="-"){ cout << "NOT POSSIBLE"; return 0; }
    else cout << ans;
}

Compilation message (stderr)

friends.cpp: In function 'bool solve(std::__cxx11::string, std::__cxx11::string)':
friends.cpp:22:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(lp>=p.length() or lt>=t.length()) break;
            ~~^~~~~~~~~~~~
friends.cpp:22:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(lp>=p.length() or lt>=t.length()) break;
                              ~~^~~~~~~~~~~~
friends.cpp:32:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(l+r>=p.length()){ ans = p; return true; }
        ~~~^~~~~~~~~~~~

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