1207. Unique Number of Occurrences

# 1207. Unique Number of Occurrences#

## 题目 #

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`

## 题目大意 #

• 1 <= arr.length <= 1000
• -1000 <= arr[i] <= 1000

## 解题思路 #

• 给出一个数组，先统计每个数字出现的频次，判断在这个数组中是否存在相同的频次。
• 简单题，先统计数组中每个数字的频次，然后用一个 map 判断频次是否重复。

## 代码 #

``````
package leetcode

func uniqueOccurrences(arr []int) bool {
freq, m := map[int]int{}, map[int]bool{}
for _, v := range arr {
freq[v]++
}
for _, v := range freq {
if _, ok := m[v]; !ok {
m[v] = true
} else {
return false
}
}
return true
}

``````

Sep 6, 2020