[20260321] BOJ / G5 / 4와 7 / 이준희

JHLEE325/202603/21 BOJ G5 4와 7.md

@@ -0,0 +1,25 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int K = Integer.parseInt(br.readLine());
+
+        String binary = Integer.toBinaryString(K + 1);
+
+        StringBuilder sb = new StringBuilder();
+        for (int i = 1; i < binary.length(); i++) {
+            if (binary.charAt(i) == '0') {
+                sb.append('4');
+            } else {
+                sb.append('7');
+            }
+        }
+
+        System.out.println(sb.toString());
+    }
+}
+```

JHLEE325/202603/22 BOJ G5 간선 이어가기 2.md

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+```java
+import java.io.*;
+import java.util.*;
+
+class Node implements Comparable<Node> {
+    int target, weight;
+
+    public Node(int target, int weight) {
+        this.target = target;
+        this.weight = weight;
+    }
+
+    @Override
+    public int compareTo(Node o) {
+        return this.weight - o.weight;
+    }
+}
+
+public class Main {
+
+    static List<Node>[] adj;
+    static int[] dist;
+    static final int INF = Integer.MAX_VALUE;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        int n = Integer.parseInt(st.nextToken());
+        int m = Integer.parseInt(st.nextToken());
+
+        adj = new ArrayList[n + 1];
+        for (int i = 1; i <= n; i++) adj[i] = new ArrayList<>();
+
+        for (int i = 0; i < m; i++) {
+            st = new StringTokenizer(br.readLine());
+            int u = Integer.parseInt(st.nextToken());
+            int v = Integer.parseInt(st.nextToken());
+            int w = Integer.parseInt(st.nextToken());
+            adj[u].add(new Node(v, w));
+            adj[v].add(new Node(u, w));
+        }
+
+        st = new StringTokenizer(br.readLine());
+        int s = Integer.parseInt(st.nextToken());
+        int t = Integer.parseInt(st.nextToken());
+
+        dijkstra(n, s);
+
+        System.out.println(dist[t]);
+    }
+
+    static void dijkstra(int n, int start) {
+        dist = new int[n + 1];
+        Arrays.fill(dist, INF);
+
+        PriorityQueue<Node> pq = new PriorityQueue<>();
+        dist[start] = 0;
+        pq.add(new Node(start, 0));
+
+        while (!pq.isEmpty()) {
+            Node current = pq.poll();
+            int currNode = current.target;
+            int currWeight = current.weight;
+
+            if (dist[currNode] < currWeight) continue;
+
+            for (Node next : adj[currNode]) {
+                if (dist[next.target] > dist[currNode] + next.weight) {
+                    dist[next.target] = dist[currNode] + next.weight;
+                    pq.add(new Node(next.target, dist[next.target]));
+                }
+            }
+        }
+    }
+}
+```