LeetCode75——Day21

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;
    }
};
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