1207. Unique Number of Occurrences
- User Accepted:3828
- User Tried:3899
- Total Accepted:3925
- Total Submissions:5005
- Difficulty:Easy
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 1:
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 2:
Input: arr = [1,2] Output: false
Example 3:
Input: arr = [-3,0,1,-3,1,1,1,-3,10,0] Output: true
Constraints:
1 <= arr.length <= 1000
-1000 <= arr[i] <= 1000
BONUS:
1.dict.get 如果有key返回key,没有返回括号后面的,所以代码的意思是。如果有这个键就加一,没有就是1
2.把剩下的数值压入集合,对key值遍历,在其中出现,返回false,否则true
class Solution(object): def uniqueOccurrences(self, arr): """ :type arr: List[int] :rtype: bool """ dict = {} for key in arr: dict[key] = dict.get(key, 0) + 1 values = set() for key in dict.keys(): val = dict[key] if val in values: return False else: values.add(val) return True