LeetCode75——Day21

文章目录

• • 一、题目
  • 二、题解

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 <= arri <= 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;
    }
};