From 3d771bbabeaf460f32a27d651faa740f6d9e1faa Mon Sep 17 00:00:00 2001
From: SinnoLn <sintmtn69@gmail.com>
Date: Fri, 16 Oct 2026 18:09:50 +0900
Subject: [PATCH 1/2] 4070. Minimum Rotations to Dial a Number I

---
 ...Minimum Rotations to Dial a Number I.java" | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 "leetcode3/\354\235\264\354\247\204\355\235\254/4070. Minimum Rotations to Dial a Number I.java"

diff --git "a/leetcode3/\354\235\264\354\247\204\355\235\254/4070. Minimum Rotations to Dial a Number I.java" "b/leetcode3/\354\235\264\354\247\204\355\235\254/4070. Minimum Rotations to Dial a Number I.java"
new file mode 100644
index 00000000..f362fdc5
--- /dev/null
+++ "b/leetcode3/\354\235\264\354\247\204\355\235\254/4070. Minimum Rotations to Dial a Number I.java"	
@@ -0,0 +1,36 @@
+/*
+
+1. 아이디어 : 다이얼 크기 10 -> 시계방향, 반시계방향 회전의 경우중 더 짧은것 선택
+             
+             경우의 수 (a->b)
+             1. |a-b|
+             2. 9 - |a-b|
+
+2. 시간복잡도 : O(s 문자열 길이)
+
+3. 자료구조/알고리즘 : 그리디
+
+ */
+
+class Solution {
+    public int minRotations(String s) {
+        
+        int ans = 0;
+        int pos = 0;
+
+        for(int i=0; i<s.length(); i++) {
+            int num = s.charAt(i)-'0';
+
+            // 회전해서 갈 경우
+            // 바로 갈 경우
+
+            int cal = Math.abs(num-pos);
+
+            ans+=Math.min(cal, 10-cal);
+
+            pos = num;
+        }
+
+        return ans;
+    }
+}
\ No newline at end of file

From a533f4e9633b511a5b34f0c75bd89ba7be84b2d9 Mon Sep 17 00:00:00 2001
From: SinnoLn <sintmtn69@gmail.com>
Date: Sat, 17 Oct 2026 23:44:21 +0900
Subject: [PATCH 2/2] 1311. Get Watched Videos by Your Friends

---
 .... Get Watched Videos by Your Friends.java" | 87 +++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 "leetcode3/\354\235\264\354\247\204\355\235\254/1311. Get Watched Videos by Your Friends.java"

diff --git "a/leetcode3/\354\235\264\354\247\204\355\235\254/1311. Get Watched Videos by Your Friends.java" "b/leetcode3/\354\235\264\354\247\204\355\235\254/1311. Get Watched Videos by Your Friends.java"
new file mode 100644
index 00000000..3be2a238
--- /dev/null
+++ "b/leetcode3/\354\235\264\354\247\204\355\235\254/1311. Get Watched Videos by Your Friends.java"	
@@ -0,0 +1,87 @@
+/*
+1. 아이디어:
+   - 그래프 구조에서 특정 노드 기준 거리가 k인 노드들을 체크
+   - 그 노드들의 비디오 자료를 확인 후 커스텀 정렬 (1. 빈도수 2. 알파벳)
+   - 비디오 제목은 가짓수가 26^8이므로 hashmap 자료구조 사용
+   - 또한 friends가 이미 그래프 구조이므로 별도 그래프 구조체를 만들지 않음
+
+2. 시간복잡도: O(N + E + U log U) (N: 친구 수, E: 친구 관계 수, U: 고유 비디오 수)
+
+3. 자료구조/알고리즘: BFS + 커스텀 정렬 + HashMap
+*/
+class Solution {
+
+    private class Info {
+        String title;
+        int cnt;
+
+        public Info (String title, int cnt) {
+            this.title = title;
+            this.cnt = cnt;
+        }
+    };
+
+    public List<String> watchedVideosByFriends(List<List<String>> watchedVideos, int[][] friends, int id, int level) {
+
+        List<Integer> friend = bfs(friends, id, level);
+
+        Map<String, Integer> map = new HashMap<>();
+
+        // 비디오 계산
+        for(int i : friend) {
+            for(String video : watchedVideos.get(i)) {
+                if(!map.containsKey(video)) map.put(video, 1);
+                else map.put(video,map.get(video)+1);
+            }
+        }
+
+        List<Info> info = new ArrayList<>();
+
+        // 구조체 삽입
+        for(String key : map.keySet()) {
+            info.add(new Info(key, map.get(key)));
+        }
+
+        Collections.sort(info, (a,b) ->{
+            if(a.cnt == b.cnt) return a.title.compareTo(b.title);
+            return a.cnt - b.cnt;
+        });
+
+        List<String> ans = new ArrayList<>();
+        
+        for(Info i : info) {
+            ans.add(i.title);
+        }
+
+        return ans;
+    }
+
+    private List<Integer> bfs(int[][] friends, int id, int level){
+        Deque<int[]> dq= new ArrayDeque<>();
+        boolean[] visited= new boolean[friends.length];
+
+        List<Integer> friend = new ArrayList<>();
+        
+        dq.add(new int[]{id, 0});
+        visited[id] = true;
+
+        while(!dq.isEmpty()) {
+            int curr[] = dq.poll();
+
+            int currId = curr[0];
+            int depth = curr[1];
+
+            if(depth == level) friend.add(currId);
+
+            for(int next : friends[currId]) {
+
+                if(visited[next] || depth>level) continue;
+
+                dq.add(new int[]{next,depth+1});
+                visited[next] = true;
+            }
+        }
+
+        return friend;
+    }
+}
\ No newline at end of file