JavaCote · leesangeok · Feb 5, 2026
diff --git a/week40/이상억/backjoon/2배_또는_0.5배.java b/week40/이상억/backjoon/2배_또는_0.5배.java
@@ -0,0 +1,17 @@
+import java.util.*;
+import java.io.*;
+
+public class Main{
+    public static void main(String[] args) throws IOException{
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+
+        int N = Integer.parseInt(br.readLine());
+
+
+
+    }
+}
+
+
+//
diff --git a/week40/이상억/backjoon/숫자_고르기.java b/week40/이상억/backjoon/숫자_고르기.java
@@ -0,0 +1,56 @@
+import java.util.*;
+import java.io.*;
+
+public class Main {
+
+    static int[] next;
+    static boolean[] visited;
+    static boolean[] finished;
+    static List<Integer> answer = new ArrayList<>();
+
+    static void dfs(int cur) {
+        visited[cur] = true;
+        int nxt = next[cur];
+
+        if (!visited[nxt]) {
+            dfs(nxt);
+        }
+        else if (!finished[nxt]) {
+            int temp = nxt;
+            answer.add(temp);
+
+            while (temp != cur) {
+                temp = next[temp];
+                answer.add(temp);
+            }
+        }
+
+        finished[cur] = true;
+    }
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        int N = Integer.parseInt(br.readLine());
+
+        next = new int[N + 1];
+        visited = new boolean[N + 1];
+        finished = new boolean[N + 1];
+
+        for (int i = 1; i <= N; i++) {
+            next[i] = Integer.parseInt(br.readLine());
+        }
+
+        for (int i = 1; i <= N; i++) {
+            if (!visited[i]) {
+                dfs(i);
+            }
+        }
+
+        Collections.sort(answer);
+        System.out.println(answer.size());
+        for (int x : answer) {
+            System.out.println(x);
+        }
+    }
+}
diff --git a/week40/이상억/progarmmers/섬_연결하기.java b/week40/이상억/progarmmers/섬_연결하기.java
@@ -0,0 +1,56 @@
+import java.util.*;
+
+class Solution {
+
+    class Edge {
+        int to;
+        int cost;
+
+        Edge(int to, int cost) {
+            this.to = to;
+            this.cost = cost;
+        }
+    }
+
+    public int solution(int n, int[][] costs) {
+
+        List<Edge>[] graph = new ArrayList[n];
+        for (int i = 0; i < n; i++) {
+            graph[i] = new ArrayList<>();
+        }
+
+        for (int[] c : costs) {
+            int from = c[0];
+            int to = c[1];
+            int cost = c[2];
+
+            graph[from].add(new Edge(to, cost));
+            graph[to].add(new Edge(from, cost));
+        }
+
+        boolean[] visited = new boolean[n];
+        PriorityQueue<Edge> pq = new PriorityQueue<>(
+                (a, b) -> a.cost - b.cost
+        );
+
+        pq.add(new Edge(0, 0));
+        int answer = 0;
+
+        while (!pq.isEmpty()) {
+            Edge cur = pq.poll();
+
+            if (visited[cur.to]) continue;
+
+            visited[cur.to] = true;
+            answer += cur.cost;
+
+            for (Edge next : graph[cur.to]) {
+                if (!visited[next.to]) {
+                    pq.add(next);
+                }
+            }
+        }
+
+        return answer;
+    }
+}
diff --git a/week40/이상억/progarmmers/추석_트래픽.java b/week40/이상억/progarmmers/추석_트래픽.java
@@ -0,0 +1,73 @@
+import java.util.*;
+
+class Solution {
+
+    static class Log{
+        int start;
+        int end;
+
+        Log(int start, int end){
+            this.start = start;
+            this.end = end;
+        }
+    }
+
+
+    static Log parse(String line){
+        String[] parts = line.split(" ");
+
+        String[] time = parts[1].split(":");
+
+        int hh = Integer.parseInt(time[0]);
+        int mm = Integer.parseInt(time[1]);
+
+        String[] sec = time[2].split("\\.");
+        int ss = Integer.parseInt(sec[0]);
+        int ms = Integer.parseInt(sec[1]);
+
+        int endMs = hh * 3600000 +
+                mm * 60000 +
+                ss * 1000 +
+                ms;
+
+        double durationSec = Double.parseDouble(
+                parts[2].substring(0, parts[2].length() - 1)
+        );
+
+        int durationMs = (int)(durationSec * 1000);
+
+        int startMs = endMs - durationMs + 1;
+
+        return new Log(startMs, endMs);
+
+    }
+
+
+    public int solution(String[] lines) {
+        int answer = 0;
+
+        List<Log> logs = new ArrayList<>();
+
+        for(String line : lines){
+            logs.add(parse(line));
+        }
+
+        for(Log base : logs){
+            int windowStart = base.end;
+            int windowEnd = base.end + 999;
+
+            int count = 0;
+            for(Log target : logs){
+                if(target.start <= windowEnd && target.end >= windowStart){
+                    count ++;
+                }
+            }
+
+            answer = Math.max(answer, count);
+        }
+        return answer;
+    }
+}
+
+// window :      [======]
+// target :  [-----------]