solve problem Contains Duplicate

Author: P-ppc

README.md

@@ -46,6 +46,7 @@ All solutions will be accepted!
 |231|[Power Of Two](https://leetcode-cn.com/problems/power-of-two/description/)|[java/py/js](./algorithms/PowerOfTwo)|Easy|
 |38|[Count And Say](https://leetcode-cn.com/problems/count-and-say/description/)|[java/py/js](./algorithms/CountAndSay)|Easy|
 |383|[Ransom Note](https://leetcode-cn.com/problems/ransom-note/description/)|[java/py/js](./algorithms/RansomNote)|Easy|
+|217|[Contains Duplicate](https://leetcode-cn.com/problems/contains-duplicate/description/)|[java/py/js](./algorithms/ContainsDuplicate)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/ContainsDuplicate/README.md

@@ -0,0 +1,2 @@
+# Contains Duplicate
+This problem is easy to solve by hashmap

algorithms/ContainsDuplicate/Solution.java

@@ -0,0 +1,13 @@
+class Solution {
+    public boolean containsDuplicate(int[] nums) {
+        Map<Integer, Boolean> intMap = new HashMap<Integer, Boolean>();
+        for (int num : nums) {
+            if (intMap.get(num) == null) {
+                intMap.put(num, true);
+            } else {
+                return true;
+            }
+        }
+        return false;
+    }
+}

algorithms/ContainsDuplicate/solution.js

@@ -0,0 +1,16 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function(nums) {
+    let intMap = {}
+    for (let i = 0; i < nums.length; i++) {
+        let num = nums[i]
+        if (intMap[num] === undefined) {
+            intMap[num] = true
+        } else {
+            return true
+        }
+    }
+    return false
+};

algorithms/ContainsDuplicate/solution.py

@@ -0,0 +1,13 @@
+class Solution(object):
+    def containsDuplicate(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: bool
+        """
+        int_map = {}
+        for num in nums:
+            if int_map.get(num) == None:
+                int_map[num] = True
+            else:
+                return True
+        return False