'commit'

TangDou/51NOD/1909.cpp

@@ -34,13 +34,14 @@ aaa
 第i行，第j个
 i从1开始，到n=4结束
 j从1开始，到i结束
+找出递推关系式：
 x=n-i + (j-1)*2
 y=(n-i)*sqrt(3)
-
 */
 
 bool check(Node a, Node b, Node c) {
-    //  n - i + (j - 1) * 2, (n - i) * sqrt(3)
+    // x= n - i + (j - 1) * 2
+    // y= (n - i) * sqrt(3)
     if (a.c != b.c || a.c != c.c || b.c != c.c) return false;
 
     double ax = (n - a.x + (a.y - 1) * 2);
@@ -63,8 +64,8 @@ int main() {
     freopen("51nod_1909_2_in.txt", "r", stdin);
 #endif
 
-    cin >> n;
-    string s;
+    cin >> n; // 4
+    string s; // abccddadca
     cin >> s;
     // 先把字符串存入char[][]
     int idx = 0;

TangDou/51NOD/kapibala.cpp

@@ -0,0 +1,49 @@
+#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;
+}