Submission #38479

#	Time	Username	Problem	Language	Result	Execution time	Memory
38479		Waschbar	Three Friends (BOI14_friends)	C++14	0 / 100	76 ms	7860 KiB

friends

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

int cnt[100];

int main() {
	
	string s;
	int n;
	cin >> n;
	cin >> s;
	
	if(n%2 == 0) {
		cout << "NOT POSSIBLE";
		return 0;
	}
	
	for(int i = 0; i < n; i++)
		cnt[s[i]-'A']++;
	
	char ch;
	int tmp = 0;
	for(int i = 0; i < 30; i++) 
		if(cnt[i]%2) tmp++,ch = (char)('A'+i);
	
	if(tmp != 1) {
		cout << "NOT POSSIBLE";
		return 0;	
	}
	
	int x1, x2, y1, y2;
	bool ind = 0;
	x1 = n/2; x2 = n-1;
	y1 = y2 = -1;
	while(x1 >= 0 && x2 > n/2) {
		if(s[x1] != s[x2] && s[x1] == ch){
			y1 = x1;
			if((x1 > 0 && s[x1-1] == ch) || (x1 < n/2 && s[x1+1] == ch)) ind = 1;
			break;
		}
		x1--; x2--;
	}
	if(x1 >= 0 && x2 <= n/2 && s[x1] == ch){
			y1 = x1; 
			if((x1 > 0 && s[x1-1] == ch) || (x1 < n/2 && s[x1+1] == ch)) ind = 1;
		}
	
	x1 = n/2-1; x2 = n-1;
	while(x1 >= 0 && x2 >= n/2) {
		if(s[x1] != s[x2] && s[x2] == ch){
			y2 = x2;
			if((x2 > n/2 && s[x2-1] == ch) || (x2 < n-1 && s[x2+1] == ch)) ind = 1;
			break;
		}
		x1--; x2--;
	}
	if(x1 > 0 && x2 <= n/2 && s[x2] == ch){
			y2 = x2;
			if((x2 > n/2 && s[x2-1] == ch) || (x2 < n-1 && s[x2+1] == ch)) ind = 1;
		}
	
//	cout << y1 << " " << y2 << " " << ch << endl;
	
	
	if(y1 == -1 && y2 == -1) {
		cout << "NOT POSSIBLE";
		return 0;
	}
	
	if(y1 != -1) {
		x1 = 0; x2 = n/2+1;
		if(x1 == y1) x1++;
		while(x1 <= n/2) {
			if(s[x1] != s[x2]) {
				cout << "NOT POSSIBLE";
				return 0;		
			}
			x1++; x2++;
			if(x1 == y1) x1++;
		}
	}
	else {
		x1 = 0; x2 = n/2;
		if(x2 == y2) x2++;
		while(x1 < n/2) {
			if(s[x1] != s[x2]) {
				cout << "NOT POSSIBLE";
				return 0;		
			}
			x1++; x2++;
			if(x2 == y2) x2++;
		}
	}
	
	if(y1 != y2 && y1 != -1 && y2 != -1) ind = 1;
	
	if(ind){
		cout <<"NOT UNIQUE";
		return 0;
	}
	
	if(y1 != -1) {
		x1 = 0; x2 = n/2+1;
		if(x1 == y1) x1++;
		while(x1 <= n/2) {
			cout << s[x1];
			x1++; x2++;
			if(x1 == y1) x1++;
		}
	}
	else {
		x1 = 0; x2 = n/2;
		if(x2 == y2) x2++;
		while(x1 < n/2) {
			cout << s[x2];
			x1++; x2++;
			if(x2 == y2) x2++;
		}
	}
	
}

Compilation message (stderr)

friends.cpp: In function 'int main()':
friends.cpp:38:46: warning: 'ch' may be used uninitialized in this function [-Wmaybe-uninitialized]
    if((x1 > 0 && s[x1-1] == ch) || (x1 < n/2 && s[x1+1] == ch)) ind = 1;
                                              ^

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