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 #

给你一个整数数组 arr,请你帮忙统计数组中每个数的出现次数。如果每个数的出现次数都是独一无二的,就返回 true;否则返回 false。

提示:

  • 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
}


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