adding set leetcode problem

lectures/16_maps_II/README.md

@@ -65,8 +65,9 @@ map_vect :: const_iterator p;
 
 The compiler makes the substitution for you.
 
-## 16.10 Leetcode Exercises
+## 16.3 Leetcode Exercises
 
 - [Leetcode problem 49: Group Anagrams](https://leetcode.com/problems/group-anagrams/). Solution: [p49_group_anagrams.cpp](../../leetcode/p49_group_anagrams.cpp).
 - [Leetcode problem 290: Word Pattern](https://leetcode.com/problems/word-pattern/). Solution: [p290_word_pattern.cpp](../../leetcode/p290_word_pattern.cpp).
+- [Leetcode problem 1207: Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences/). Solution: [p1207_unique_number_occurrences.cpp](../../leetcode/p1207_unique_number_occurrences.cpp).
 

leetcode/p1207_unique_number_occurrence.cpp

@@ -0,0 +1,26 @@
+class Solution {
+public:
+    bool uniqueOccurrences(vector<int>& arr) {
+        int size = arr.size();
+        // key: number, value: occurrence
+        std::map<int, int> map1;
+        std::set<int> set1;
+        // create the map
+        for(int i=0; i<size; i++){
+            map1[arr[i]]++;
+        }
+        // use the map
+        std::map<int, int>::iterator itr;
+        itr = map1.begin();
+        while(itr != map1.end()){
+            // if this number of occurrence already exists
+            if(set1.find(itr->second) != set1.end()){
+                return false;
+            }
+            // otherwise, store it.
+            set1.insert(itr->second);
+            itr++;
+        }
+        return true;
+    }
+};