Create solution.cpp

Author: aishsingh

ContainsDuplicateII/solution.cpp

@@ -0,0 +1,30 @@
+#include <unordered_map>
+
+class Solution {
+public:
+    bool containsNearbyDuplicate(vector<int>& nums, int k) 
+    {
+        // Store indices with the keys are their values
+        unordered_map<int, int> hashmap;
+
+        for (int i=0; i<nums.size(); i++)
+        {
+            // Check if the current value was added before
+            if (hashmap.count(nums.at(i)))
+            {
+                // The current value is a duplicate
+                // Check if the current index and past index are within k appart
+                if (i - hashmap[nums.at(i)] <= k)
+                {
+                    return true;
+                }
+            }
+
+            // Add new index and value to hashmap
+            hashmap[nums.at(i)] = i;
+        }   
+
+        // No duplicates were within k if we reached here
+        return false; 
+    }
+};