1636. Sort Array by Increasing Frequency

题目

Given an array of integers nums, sort the array in increasing order based on the frequency of the values. If multiple values have the same frequency, sort them in decreasing order.

Return the sorted array.

Example 1:

Input: nums = [1,1,2,2,2,3]
Output: [3,1,1,2,2,2]
Explanation: '3' has a frequency of 1, '1' has a frequency of 2, and '2' has a frequency of 3.

Example 2:

Input: nums = [2,3,1,3,2]
Output: [1,3,3,2,2]
Explanation: '2' and '3' both have a frequency of 2, so they are sorted in decreasing order.

Example 3:

Input: nums = [-1,1,-6,4,5,-6,1,4,1]
Output: [5,-1,4,4,-6,-6,1,1,1]

Constraints:

1 <= nums.length <= 100
100 <= nums[i] <= 100

题目大意

给你一个整数数组 nums ，请你将数组按照每个值的频率升序排序。如果有多个值的频率相同，请你按照数值本身将它们降序排序。请你返回排序后的数组。

解题思路

简单题。先统计每个值的频率，然后按照频率从小到大排序，相同频率的按照值的大小，从大到小排序。

代码

package leetcode

import "sort"

func frequencySort(nums []int) []int {
	freq := map[int]int{}
	for _, v := range nums {
		freq[v]++
	}
	sort.Slice(nums, func(i, j int) bool {
		if freq[nums[i]] == freq[nums[j]] {
			return nums[j] < nums[i]
		}
		return freq[nums[i]] < freq[nums[j]]
	})
	return nums
}