1472-design-browser-history.go

package main

import "math"

func main() {
	
}

type BrowserHistory struct {
	history []string
	current int
}

func Constructor(homepage string) BrowserHistory {
	return BrowserHistory{
		history: []string{homepage},
		current: 0,
	}
}

func (this *BrowserHistory) Visit(url string) {
	this.history = this.history[0: this.current + 1]
	this.history = append(this.history, url)
	this.current++
}

func (this *BrowserHistory) Back(steps int) string {
	this.current = int(math.Max(float64(this.current) - float64(steps), 0))
	return this.history[this.current]
}

func (this *BrowserHistory) Forward(steps int) string {
	this.current = int(math.Min(float64(this.current) +float64(steps), float64(len(this.history) - 1)))
	return this.history[this.current]
}