Create valid-square.cpp

Author: kamyu104

C++/valid-square.cpp

@@ -0,0 +1,18 @@
+// Time:  O(1)
+// Space: O(1)
+
+class Solution {
+public:
+    bool validSquare(vector<int>& p1, vector<int>& p2, vector<int>& p3, vector<int>& p4) {
+        unordered_set<int> s({ d(p1, p2), d(p1, p3),
+                               d(p1, p4), d(p2, p3),
+                               d(p2, p4), d(p3, p4) });
+        return !s.count(0) && s.size() == 2;
+    }
+
+private:
+    int d(vector<int>& p1, vector<int>& p2) {
+        return (p1[0] - p2[0]) * (p1[0] - p2[0]) +
+               (p1[1] - p2[1]) * (p1[1] - p2[1]);
+    }
+};