From f22a59ac9d9065cbf02a5134010c3cecc171a270 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=BB=84=E6=B5=B7?= <10402852@qq.com>
Date: Sat, 20 Jan 2024 17:18:15 +0800
Subject: [PATCH] 'commit'

---
 TangDou/LuoGuBook/ZhiMuSanJiaoXing.cpp | 42 ++++++++++++++++++++++----
 TangDou/LuoGuBook/ZhiMuSanJiaoXing.in  |  4 +--
 2 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/TangDou/LuoGuBook/ZhiMuSanJiaoXing.cpp b/TangDou/LuoGuBook/ZhiMuSanJiaoXing.cpp
index 9b8580a..b79ff1b 100644
--- a/TangDou/LuoGuBook/ZhiMuSanJiaoXing.cpp
+++ b/TangDou/LuoGuBook/ZhiMuSanJiaoXing.cpp
@@ -4,6 +4,9 @@ char a[N][N];
 /*
 4
 abccddadca
+
+2
+aaa
 */
 using namespace std;
 
@@ -12,6 +15,27 @@ struct Node {
     char c;
 };
 vector<Node> q;
+/*
+把半径当做 1 ，建立坐标系，然后枚举就行了，需要注意的是，在判断三条边的长度是否相等时用 double 牵扯到精度问题，
+解决方法是:比较长度的平方，长度的平方肯定是整数，还有就是层层之间纵坐标相差是sqrt(3) 的倍数，
+为了不牵扯到小数，把纵坐标的 sqrt(3) 当做1 ，求边长时乘三即可。
+*/
+int pf(int x) {
+    return x * x;
+}
+
+bool check(Node a, Node b, Node c) {
+    cout << "a.x=" << a.x << ",a.y=" << a.y << endl;
+    cout << "b.x=" << b.x << ",b.y=" << a.y << endl;
+    cout << "c.x=" << c.x << ",c.y=" << a.y << endl;
+
+    // a与b之间距离 不等于 a与c之间距离
+    if (pf(a.x - b.x) + pf(a.y - b.y) * 3 != pf(a.x - c.x) + pf(a.y - c.y) * 3) return false;
+    // a与b之间距离 不等于 b与c之间距离
+    if (pf(a.x - b.x) + pf(a.y - b.y) * 3 != pf(b.x - c.x) + pf(b.y - c.y) * 3) return false;
+
+    return true;
+}
 
 int main() {
 #ifndef ONLINE_JUDGE
@@ -29,16 +53,22 @@ int main() {
 
     // 把所有坐标记录下来
     for (int i = 0; i < n; i++) {
-        for (int j = 0; j <= i; j++)
-            q.push_back({i, j, a[i][j]});
+        for (int j = 0; j <= i; j++) {
+            q.push_back({n - 1 - i, j, a[i][j]});
+            // cout << "x=" << n - 1 - i << ",y=" << j << " " << a[i][j] << endl;
+        }
     }
+
     vector<char> res;
     // 在q数组中，选择任意三个，计算两两间距离是不是相等
     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++) {
-                Node x = q[i], y = q[j], z = q[k];
-                if (check()) res.push_back(x.c);
+        for (int j = 0; j < q.size(); j++)
+            for (int k = 0; k < q.size(); k++) {
+                if (i == j || i == k || j == k) continue;
+
+                if (q[i].c != q[j].c || q[i].c != q[k].c || q[j].c != q[k].c) continue;
+                if (check(q[i], q[j], q[k]))
+                    res.push_back(q[i].c);
             }
 
     if (res.size() == 0)
diff --git a/TangDou/LuoGuBook/ZhiMuSanJiaoXing.in b/TangDou/LuoGuBook/ZhiMuSanJiaoXing.in
index 7f7dc01..0ae8f7f 100644
--- a/TangDou/LuoGuBook/ZhiMuSanJiaoXing.in
+++ b/TangDou/LuoGuBook/ZhiMuSanJiaoXing.in
@@ -1,2 +1,2 @@
-4
-abccddadca
\ No newline at end of file
+2
+aaa
\ No newline at end of file