add number-of-boomerangs.py

Author: lightmen

python/hash-table/number-of-boomerangs.py

@@ -0,0 +1,21 @@
+class Solution(object):
+    def dist(self, x1, y1, x2, y2):
+        return (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1)
+
+    def numberOfBoomerangs(self, points):
+        """
+        :type points: List[List[int]]
+        :rtype: int
+        """
+        ret = 0
+        for i in range(len(points)):
+            d = {}
+            for j in range(len(points)):
+                if i == j:
+                    continue
+                key = self.dist(points[i][0], points[i][1], \
+                    points[j][0], points[j][1])
+                ret += (2 * d.get(key,0))
+                d[key] = d.get(key, 0) + 1
+
+        return ret