[20250625] BOJ / G4 / 최소 스패닝 트리 / 설진영

Seol-JY/202506/25 BOJ G4 최소 스패닝 트리.md

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+```java
+import java.util.*;
+import java.io.*;
+
+public class Main {
+    static int[] parent;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        int V = Integer.parseInt(st.nextToken());
+        int E = Integer.parseInt(st.nextToken());
+
+        List<Edge> edgeList = new ArrayList<>();
+        parent = new int[V + 1];
+
+        for (int i = 1; i <= V; i++) {
+            parent[i] = i;
+        }
+
+        for (int i = 0; i < E; i++) {
+            st = new StringTokenizer(br.readLine());
+            int a = Integer.parseInt(st.nextToken());
+            int b = Integer.parseInt(st.nextToken());
+            int weight = Integer.parseInt(st.nextToken());
+            edgeList.add(new Edge(a, b, weight));
+        }
+
+        edgeList.sort((e1, e2) -> Integer.compare(e1.weight, e2.weight));
+
+        int total = 0;
+        int count = 0;
+
+        for (Edge edge : edgeList) {
+            if (find(edge.from) != find(edge.to)) {
+                union(edge.from, edge.to);
+                total += edge.weight;
+                count++;
+                if (count == V - 1) break;
+            }
+        }
+
+        System.out.println(total);
+    }
+
+    static int find(int x) {
+        if (parent[x] == x) return x;
+        return parent[x] = find(parent[x]);
+    }
+
+    static void union(int a, int b) {
+        int rootA = find(a);
+        int rootB = find(b);
+        if (rootA != rootB) parent[rootB] = rootA;
+    }
+
+    static class Edge {
+        int from, to, weight;
+
+        Edge(int from, int to, int weight) {
+            this.from = from;
+            this.to = to;
+            this.weight = weight;
+        }
+    }
+}
+
+```