Overview

An input string is given. The objective is to sort the string based on frequency. We have to sort based on decreasing order of the frequency of characters. Let’s understand it with an example

Example 1

Input: "bcabcb"
Output: "bbbcca"

Example 2

Input: "mniff"
Output: "ffmni"

Program

Below is the program for the same

package main
import (
"fmt"
"sort"
)
func frequencySort(s string) string {
stringMap := make(map[byte]int)
lenS := len(s)
for i := 0; i < lenS; i++ {
stringMap[s[i]]++
}
itemArray := make([]item, 0)
for key, value := range stringMap {
i := item{
char: key,
frequency: value,
}
itemArray = append(itemArray, i)
}
sort.Slice(itemArray, func(i, j int) bool {
return itemArray[i].frequency > itemArray[j].frequency
})
output := ""
for i := 0; i < len(itemArray); i++ {
for j := 0; j < itemArray[i].frequency; j++ {
output = output + string(itemArray[i].char)
}
}
return output
}
type item struct {
char byte
frequency int
}
func main() {
output := frequencySort("bcabcb")
fmt.Println(output)
output = frequencySort("mniff")
fmt.Println(output)
}

Output:

bbbcca
ffmni

Note: Check out our Golang Advanced Tutorial. The tutorials in this series are elaborative and we have tried to cover all concepts with examples. This tutorial is for those who are looking to gain expertise and a solid understanding of golang - Golang Advance Tutorial

Also if you are interested in understanding how all design patterns can be implemented in Golang. If yes, then this post is for you - All Design Patterns Golang

Also, check out our system design tutorial series here - System Design Tutorial Series