0380-insert-delete-getrandom-o1.go

import"math/rand"

typeRandomizedSetstruct {
hashmap[int]int
array []int
lengthint
}

funcConstructor() RandomizedSet {
returnRandomizedSet{
hash: make(map[int]int),
array: []int{},
length: 0,
 }
}

func (this*RandomizedSet) Insert(valint) bool {
if_, ok:=this.hash[val]; ok {
returnfalse
 }
this.array=append(this.array, val)
this.hash[val] =len(this.array) -1
this.length++
returntrue
}

func (this*RandomizedSet) Remove(valint) bool {
idx, ok:=this.hash[val]
if!ok {
returnfalse
 }
last:=this.array[this.length-1]
this.array[idx] =last
this.hash[last] =idx
this.array=this.array[:len(this.array)-1]
delete(this.hash, val)
this.length--
returntrue
}

func (this*RandomizedSet) GetRandom() int {
returnthis.array[rand.Intn(this.length)]
}