solve problem Number Of Boomerangs

Author: P-ppc

README.md

@@ -101,6 +101,7 @@ All solutions will be accepted!
 |661|[Image Smoother](https://leetcode-cn.com/problems/image-smoother/description/)|[java/py/js](./algorithms/ImageSmoother)|Easy|
 |598|[Range Addition II](https://leetcode-cn.com/problems/range-addition-ii/description/)|[java/py/js](./algorithms/RangeAdditionII)|Easy|
 |492|[Construct The Rectangle](https://leetcode-cn.com/problems/construct-the-rectangle/description/)|[java/py/js]|(./algorithms/ConstructTheRectangle)|Easy|
+|447|[Number Of Boomerangs](https://leetcode-cn.com/problems/number-of-boomerangs/description/)|[java/py/js](./algorithms/NumberOfBoomerangs)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/NumberOfBoomerangs/README.md

@@ -0,0 +1,2 @@
+# Number Of Boomerangs
+This problem is easy to solve by hashmap

algorithms/NumberOfBoomerangs/Solution.java

@@ -0,0 +1,20 @@
+class Solution {
+    public int numberOfBoomerangs(int[][] points) {
+        int count = 0;
+        
+        for (int[] point : points) {
+            Map<Integer, Integer> distanceMap = new HashMap<Integer, Integer>();
+            for (int[] p : points) {
+                int distance = (int) Math.pow(point[0] - p[0], 2) + (int) Math.pow(point[1] - p[1], 2);
+                if (distanceMap.get(distance) == null) {
+                    distanceMap.put(distance, 1);
+                } else {
+                    count += 2 * distanceMap.get(distance);
+                    distanceMap.put(distance, distanceMap.get(distance) + 1);
+                }
+            }
+        }
+        
+        return count;
+    }
+}

algorithms/NumberOfBoomerangs/solution.js

@@ -0,0 +1,22 @@
+/**
+ * @param {number[][]} points
+ * @return {number}
+ */
+var numberOfBoomerangs = function(points) {
+    let count = 0
+    
+    points.forEach(point => {
+        let distanceMap = new Map()
+        points.forEach(p => {
+            let distance = Math.pow(point[0] - p[0], 2) + Math.pow(point[1] - p[1], 2)
+            if (distanceMap.get(distance) === undefined) {
+                distanceMap.set(distance, 1);
+            } else {
+                count += 2 * distanceMap.get(distance)
+                distanceMap.set(distance, distanceMap.get(distance) + 1)
+            }
+        })
+    })
+    
+    return count
+};

algorithms/NumberOfBoomerangs/solution.py

@@ -0,0 +1,19 @@
+class Solution(object):
+    def numberOfBoomerangs(self, points):
+        """
+        :type points: List[List[int]]
+        :rtype: int
+        """
+        count = 0
+        
+        for point in points:
+            distance_map = {}
+            for p in points:
+                distance = pow(point[0] - p[0], 2) + pow(point[1] - p[1], 2)
+                if distance_map.get(distance) == None:
+                    distance_map[distance] = 1
+                else:
+                    count += 2 * distance_map[distance]
+                    distance_map[distance] += 1
+        
+        return count