一、题目

1207. Unique Number of Occurrences

Given an array of integers arr, return true if the number of occurrences of each value in the array is unique or false otherwise.

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

二、题解

class Solution {
public:bool uniqueOccurrences(vector<int>& arr) {unordered_map<int,int> map;unordered_map<int,int> times;unordered_map<int,int>::iterator it; int n = arr.size();for(int i = 0;i < n;i++){map[arr[i]]++;}for (it = map.begin(); it != map.end();it++){if(times[map[it->first]] == 0) times[map[it->first]]++;else return false;}return true;}
};