You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

49 lines
1.5 KiB

#include <bits/stdc++.h>
using namespace std;
const int N = 110;
char a[N][N];
const double eps = 1e-8;
int n;
struct Node {
int x, y;
char c;
};
vector<Node> q;
bool check(Node a, Node b, Node c) {
if (a.c != b.c || a.c != c.c || b.c != c.c) return false;
double ax = (n - a.x + (a.y - 1) * 2);
double bx = (n - b.x + (b.y - 1) * 2);
double cx = (n - c.x + (c.y - 1) * 2);
double ay = (n - a.x) * sqrt(3);
double by = (n - b.x) * sqrt(3);
double cy = (n - c.x) * sqrt(3);
double c1 = (ax - bx) * (ax - bx) + (ay - by) * (ay - by);
double c2 = (ax - cx) * (ax - cx) + (ay - cy) * (ay - cy);
double c3 = (bx - cx) * (bx - cx) + (by - cy) * (by - cy);
if (abs(c1 - c2) < eps && abs(c1 - c3) < eps && abs(c2 - c3) < eps) return true;
return false;
}
int main() {
cin >> n;
string s;
cin >> s;
int idx = 0;
for (int i = 1; i <= n; i++)
for (int j = 1; j <= i; j++)
a[i][j] = s[idx++];
for (int i = 1; i <= n; i++)
for (int j = 1; j <= i; j++)
q.push_back({i, j, a[i][j]});
vector<char> res;
for (int i = 0; i < q.size(); i++)
for (int j = i + 1; j < q.size(); j++)
for (int k = j + 1; k < q.size(); k++)
if (check(q[i], q[j], q[k])) res.push_back(q[i].c);
if (res.size() == 0)
cout << "No Solution" << endl;
else{
sort(res.begin(), res.end());
for (char x : res) cout << x;
}
return 0;
}