Merge pull request neetcode-gh#1461 from Kongx231/create-211-duplicate-numbers-2

Create 219-Contains-Duplicate-II.cpp

Author: Ahmad-A0

cpp/219-Contains-Duplicate-II.cpp

@@ -0,0 +1,15 @@
+class Solution {
+public:
+    bool containsNearbyDuplicate(vector<int>& nums, int k) {
+        unordered_map<int,int> number_map;
+        for (int i = 0; i < nums.size(); ++i) {
+            int num = nums[i];
+            if (number_map.find(num) != number_map.end() && i - number_map[num] <= k) {
+                return true;
+            }else {
+                number_map[num] = i;
+            }
+        }
+        return false;
+    }
+};