Submission #930728

#	Time	Username	Problem	Language	Result	Execution time	Memory
930728		shoryu386	Three Friends (BOI14_friends)	C++17	100 / 100	18 ms	17320 KiB

friends

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

#define int long long

main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	
	int n;
	cin >> n;
	
	if (n % 2 == 0) {cout << "NOT POSSIBLE"; return 0;}
	
	string s; cin >> s;
	

	set<string> ans;
	
	string ls = "", rs = "";
	for (int x = 0; x < n/2; x++) ls.push_back(s[x]);
	for (int x = n/2 + 1; x < n; x++) rs.push_back(s[x]);
	
	if (ls == rs){
		ans.insert(ls);
	} 
	
	string lcomp = ls, rcomp = rs;
	
	ls.push_back(s[n/2]);
	rs = s[n/2] + rs;
	
	bool lprepass[n]; memset(lprepass, 0, sizeof(lprepass));
	bool lpostpass[n]; memset(lpostpass, 0, sizeof(lpostpass));
	for (int x = 0; x < n/2; x++){
		if (ls[x] == rcomp[x]){
			lprepass[x] = 1;
		}
		else break;
	}
	
	for (int x = n/2+1; x > 0; x--){
		if (ls[x] == rcomp[x-1]){
			lpostpass[x] = 1;
		}
		else break;
	}
	
	if (lpostpass[1]) ans.insert(rcomp);
	for (int x = 0; x < n/2; x++){
		if (lprepass[x] && lpostpass[x+2]){
			ans.insert(rcomp);
			break;
		}
	}
	if (lprepass[n/2 - 1]) ans.insert(rcomp);
	
	bool rprepass[n]; memset(rprepass, 0, sizeof(rprepass));
	bool rpostpass[n]; memset(rpostpass, 0, sizeof(rpostpass));
	for (int x = 0; x < n/2; x++){
		if (rs[x] == lcomp[x]){
			rprepass[x] = 1;
		}
		else break;
	}
	
	for (int x = n/2+1; x > 0; x--){
		if (rs[x] == lcomp[x-1]){
			rpostpass[x] = 1;
		}
		else break;
	}
	
	if (rpostpass[1]) ans.insert(lcomp);
	for (int x = 0; x < n/2; x++){
		if (rprepass[x] && rpostpass[x+2]){
			ans.insert(lcomp);
			break;
		}
	}
	if (rprepass[n/2 - 1]) ans.insert(lcomp);
	
	if (ans.size() == 0) cout << "NOT POSSIBLE";
	else if (ans.size() == 1) cout << *ans.begin();
	else cout << "NOT UNIQUE";
	
}

Compilation message (stderr)

friends.cpp:6:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    6 | main(){
      | ^~~~

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