Create 0355-design-twitter.go

Accepted submission: _https://leetcode.com/submissions/detail/870783670/_

Author: AP-Repositories

go/0355-design-twitter.go

@@ -0,0 +1,87 @@
+type Tweet struct {
+    count int
+    tweetId int
+    followeeId int
+    index int
+}
+
+type TweetHeap []*Tweet
+func (h TweetHeap) Len() int           { return len(h) }
+func (h TweetHeap) Less(i, j int) bool { return h[i].count < h[j].count }
+func (h TweetHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
+func (h *TweetHeap) Push(x interface{}) {*h = append(*h, x.(*Tweet))}
+func (h *TweetHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}
+
+type Twitter struct {
+    count int
+    tweetMap map[int][]*Tweet
+    followMap map[int]map[int]bool
+}
+
+func Constructor() Twitter {
+    return Twitter{tweetMap: make(map[int][]*Tweet), followMap: make(map[int]map[int]bool)}
+}
+
+func (this *Twitter) PostTweet(userId int, tweetId int)  {
+    if _, ok := this.tweetMap[userId]; !ok {
+        this.tweetMap[userId] = make([]*Tweet, 0)
+    }
+    this.tweetMap[userId] = append(this.tweetMap[userId], &Tweet{count: this.count, tweetId: tweetId})
+    this.count -= 1
+}
+
+
+func (this *Twitter) GetNewsFeed(userId int) []int {
+    res := make([]int, 0)
+    minHeap := TweetHeap{}
+    
+    if _, ok := this.followMap[userId]; !ok {
+        this.followMap[userId] = make(map[int]bool)
+    }
+    this.followMap[userId][userId] = true;
+    for followeeId, _ := range this.followMap[userId] {
+        if _, ok := this.tweetMap[followeeId]; ok {
+            index := len(this.tweetMap[followeeId]) - 1
+            tweet := this.tweetMap[followeeId][index]
+            heap.Push(&minHeap, &Tweet{
+                count: tweet.count, 
+                tweetId: tweet.tweetId, 
+                followeeId: followeeId, 
+                index: index - 1})
+        }
+    }
+    
+    for len(minHeap) > 0 && len(res) < 10 {
+        tweet := heap.Pop(&minHeap).(*Tweet)
+        res = append(res, tweet.tweetId)
+        if tweet.index >= 0 {
+            nextTweet := this.tweetMap[tweet.followeeId][tweet.index]
+            heap.Push(&minHeap, &Tweet{count: nextTweet.count, 
+                                     tweetId: nextTweet.tweetId,
+                                     followeeId: tweet.followeeId,
+                                     index: tweet.index - 1})
+        }
+    }
+    return res
+}
+
+
+func (this *Twitter) Follow(followerId int, followeeId int)  {
+    if _, ok := this.followMap[followerId]; !ok {
+        this.followMap[followerId] = make(map[int]bool)
+    }
+    this.followMap[followerId][followeeId] = true
+}
+
+
+func (this *Twitter) Unfollow(followerId int, followeeId int)  {
+    if _, ok := this.followMap[followerId]; ok {
+        delete(this.followMap[followerId], followeeId)
+    }
+}