Golang | Leetcode Golang题解之第355题设计推特

题目：

题解：

type Twitter struct {Tweets []intUserTweets map[int][]intFollows map[int][]intIsFollowMy map[int]bool
}/** Initialize your data structure here. */
func Constructor() Twitter {// 每一次实例化的时候，都重新分配一次，这样不会造成示例重复var Tweets  []int// 某用户发的某条推特var UserTweets = make(map[int][]int)// 某用户关注了哪些用户var Follows = make(map[int][]int)var IsFollowMy = make(map[int]bool)t := Twitter{Tweets:Tweets,UserTweets:UserTweets,Follows: Follows,IsFollowMy: IsFollowMy,}return t
}/** Compose a new tweet. */
func (this *Twitter) PostTweet(userId int, tweetId int)  {// 每个人每次发推特，都记录到一个地方this.Tweets = append(this.Tweets,tweetId)// 某个用户发了推特，存到自己推特列表里this.UserTweets[userId] = append(this.UserTweets[userId],tweetId)
}/** Retrieve the 10 most recent tweet ids in the user's news feed. Each item in the news feed must be posted by users who the user followed or by the user herself. Tweets must be ordered from most recent to least recent. */
func (this *Twitter) GetNewsFeed(userId int) []int {fs := this.Follows[userId] // 先获取该用户的关注列表var allTweets []intfor _,v := range fs {// 把关注列表的人的所有推特都集中起来allTweets = append(allTweets,this.UserTweets[v]...)}if !this.IsFollowMy[userId] {// 如果自己没有关注自己，那么也需要把自己发的推特加到一起allTweets = append(allTweets,this.UserTweets[userId]...)}var sortTweets []intaTLen := len(this.Tweets)s := 0// 按照发的推特顺序进行倒序排序for i:=aTLen-1;i>=0;i-- {if s >= 10 {break}for _,n := range allTweets {// 只取 10条数据if this.Tweets[i] == n && s < 10{s++sortTweets = append(sortTweets,n)}}}return sortTweets
}/** Follower follows a followee. If the operation is invalid, it should be a no-op. */
func (this *Twitter) Follow(followerId int, followeeId int)  {// 如果自己关注了自己，标记一下if followerId == followeeId {this.IsFollowMy[followerId] = true}// 下面是判断这人是否关注了，如果已经关注了，那么就不再关注了var isFed boolfor _,v := range this.Follows[followerId] {if v == followeeId {isFed = true}}if !isFed {this.Follows[followerId] = append(this.Follows[followerId],followeeId)}
}/** Follower unfollows a followee. If the operation is invalid, it should be a no-op. */
func (this *Twitter) Unfollow(followerId int, followeeId int)  {// 如果自己取关了自己，标记一下if followeeId == followerId {this.IsFollowMy[followerId] = false}// 去掉自己关注列表里那个被关注的人var temp []intfor _,v := range this.Follows[followerId] {if v != followeeId {temp = append(temp,v)}}this.Follows[followerId] = temp
}
/*** Your Twitter object will be instantiated and called as such:* obj := Constructor();* obj.PostTweet(userId,tweetId);* param_2 := obj.GetNewsFeed(userId);* obj.Follow(followerId,followeeId);* obj.Unfollow(followerId,followeeId);*/