Problem Difficulty Level: Medium

Author: Naganathan05

Graphs/1311. Get Watched Videos by Your Friends.cpp

@@ -0,0 +1,55 @@
+/*-----------------------------
+  Time Complexity: O(V + E)
+  Space ComplexityL O(V + E)
+--------------------------------*/
+
+class Solution {
+public:
+    vector<string> watchedVideosByFriends(vector<vector<string>>& watchedVideos, vector<vector<int>>& friends, int id, int level) {
+        int n = friends.size();
+        queue<int> fifo;
+        vector<bool> visited(n, false);
+        unordered_map<string, int> freq;
+        fifo.push(id);
+        visited[id] = true;
+        int currLevel = 0;
+
+        while(!fifo.empty()){
+            int size = fifo.size();
+            if(currLevel == level) break;
+
+            for(int i = 0; i < size; i++){
+                int node = fifo.front();
+                fifo.pop();
+
+                for(int frd : friends[node]){
+                    if(!visited[frd]){
+                        fifo.push(frd);
+                        visited[frd] = true;
+                    }
+                }
+            }
+            currLevel += 1;
+        }
+
+        while(!fifo.empty()){
+            int node = fifo.front();
+            fifo.pop();
+            for(const string& video : watchedVideos[node]) freq[video] += 1;
+        }
+
+        vector<pair<string, int>> freqVector(freq.begin(), freq.end());
+        sort(freqVector.begin(), freqVector.end(), [](pair<string, int>& a, pair<string, int>& b) {
+            return a.second == b.second ? a.first < b.first : a.second < b.second;
+        });
+
+        vector<string> ans;
+        for(auto& p : freqVector) ans.push_back(p.first);
+        return ans;
+    }
+};
+
+/*
+Question Link: https://leetcode.com/problems/get-watched-videos-by-your-friends/
+Author: M.R.Naganathan
+*/