1207. Unique Number of Occurrences

Difficulty: Easy
63 / 63 test cases passed.
Runtime: 48 ms
Memory Usage: 13.8 MB

Author: YuriSpiridonov

Easy/1207.UniqueNumberofOccurrences.py

@@ -0,0 +1,38 @@
+"""
+    Given an array of integers arr, write a function that returns true if and 
+    only if the number of occurrences of each value in the array is unique.
+
+    Example:
+    Input: arr = [1,2,2,1,1,3]
+    Output: true
+    Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two 
+                 values have the same number of occurrences.
+
+    Example:
+    Input: arr = [1,2]
+    Output: false
+
+    Example:
+    Input: arr = [-3,0,1,-3,1,1,1,-3,10,0]
+    Output: true
+
+    Constraints:
+        - 1 <= arr.length <= 1000
+        - -1000 <= arr[i] <= 1000
+"""
+#Difficulty: Easy
+#63 / 63 test cases passed.
+#Runtime: 48 ms
+#Memory Usage: 13.8 MB
+
+#Runtime: 48 ms, faster than 39.33% of Python3 online submissions for Unique Number of Occurrences.
+#Memory Usage: 13.8 MB, less than 92.46% of Python3 online submissions for Unique Number of Occurrences.
+
+class Solution:
+    def uniqueOccurrences(self, arr: List[int]) -> bool:
+        digits = {}
+        for d in arr:
+            if d not in digits:
+                digits[d] = 0
+            digits[d] += 1
+        return len(digits.keys()) == len(set(digits.values()))