package main

import (
    "fmt"
    "sort"
)

type RuneSlice []rune

func (p RuneSlice) Len() int           { return len(p) }
func (p RuneSlice) Less(i, j int) bool { return p[i] < p[j] }
func (p RuneSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }

func isPermutation(str1, str2 string) bool {
    // if lengths are not equal - false
    if len(str1) == len(str2) {
        return false
    }

    // sort both strings/runes
    var rune1 RuneSlice = []rune(str1)
    var rune2 RuneSlice = []rune(str2)

    sort.Sort(rune1)
    sort.Sort(rune2)

    //fmt.Println(string(rune1[:]))
    //fmt.Println(string(rune2[:]))

    // compare rune1 and rune 2 by indexes
    for i := 0; i < len(rune1); i++ {
        if rune1[i] != rune2[i] {
            return false
        }
    }

    return true
}

func main() {
    fmt.Println("18,19,20,21 and 21,20,18,20,19,18,20 is permutation of each other : ", isPermutation("18,19,20,21", "21,20,18,20,19,18,20"))
    fmt.Println("18,19,20,21 and 21,20,18,20,18,20 is permutation of each other : ", isPermutation("18,19,20,21", "21,20,18,20,18,20"))

}

// A pumpung is a permutation of consecutive integers, possibly with repeated items.
// For example, [21, 20, 18, 20, 19, 18, 20] is pumpung
// since it is a permutation of [18, …, 21] with 18 and 20 repeated.
// However, [21, 20, 18, 20, 18, 20] is not.

package main

import "fmt"

const (
    maxInt = int(^uint(0) >> 1)
    minInt = -maxInt - 1
)

func isPumpung(a []int) (min, max int, pumpung bool) {
    min, max = maxInt, minInt
    p := make(map[int]bool)
    for _, e := range a {
        p[e] = true
        if min > e {
            min = e
        }
        if max < e {
            max = e
        }
    }
    pumpung = max-min+1 == len(p)
    if !pumpung {
        min, max = 0, 0
    }
    return min, max, pumpung
}

func isPumpungEqual(a1, a2 []int) bool {
    min1, max1, pumpung1 := isPumpung(a1)
    if !pumpung1 {
        return false
    }
    min2, max2, pumpung2 := isPumpung(a2)
    if !pumpung2 {
        return false
    }
    return min1 == min2 && max1 == max2
}

func main() {
    a1 := []int{18, 19, 20, 21}
    fmt.Print(a1, " ")
    fmt.Println(isPumpung(a1))
    a2 := []int{21, 20, 18, 20, 18, 20}
    fmt.Print(a2, " ")
    fmt.Println(isPumpung(a2))
    a3 := []int{21, 20, 18, 20, 19, 18, 20}
    fmt.Print(a3, " ")
    fmt.Println(isPumpung(a3))

    fmt.Println()
    fmt.Println(a1, a2, isPumpungEqual(a1, a2))
    fmt.Println(a1, a3, isPumpungEqual(a1, a3))
}

[18 19 20 21] 18 21 true
[21 20 18 20 18 20] 0 0 false
[21 20 18 20 19 18 20] 18 21 true

[18 19 20 21] [21 20 18 20 18 20] false
[18 19 20 21] [21 20 18 20 19 18 20] true