[20250311] BOJ / G4 / 최소 스패닝 트리 / 김수연

suyeun84/202503/11 BOJ G4 최소 스패닝 트리.md

@@ -0,0 +1,66 @@
+```java
+import java.util.*;
+import java.io.*;
+
+public class boj1197 {
+    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static StringTokenizer st;
+    static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+    static int nextInt() {return Integer.parseInt(st.nextToken());}
+
+    static ArrayList<Node> graph;
+    static int[] parent;
+    static int V, E, answer = 0;
+  	public static void main(String[] args) throws Exception {
+  		nextLine();
+  		V = nextInt();
+  		E = nextInt();
+  		int a, b, c;
+  		graph = new ArrayList<>();
+  		parent = new int[V+1];
+  		for (int i = 1; i < V+1; i++) parent[i] = i;
+
+  		for (int i = 0; i < E; i++) {
+  			nextLine();
+  			a = nextInt();
+  			b = nextInt();
+  			c = nextInt();
+  			graph.add(new Node(a, b, c));
+  		}
+
+  		graph.sort((o1, o2) -> o1.c-o2.c);
+
+  		int edgeCnt = 0;
+  		for (int i = 0; i < E; i++) {
+  			Node curr = graph.get(i);
+  			if (find(curr.s) == find(curr.e)) continue;
+  			answer += curr.c;
+  			union(curr.s, curr.e);
+  			edgeCnt++;
+  			if (edgeCnt == V-1) break;
+  		}
+  		System.out.println(answer);
+  	}
+
+  	static void union(int a, int b) {
+  		int pa = find(a);
+  		int pb = find(b);
+  		if (pa != pb) parent[pb] = pa;
+  	}
+
+  	static int find(int a) {
+  		if (parent[a] == a) return a;
+  		else return parent[a] = find(parent[a]);
+  	}
+
+  	static class Node{
+  		int s, e, c;
+  		public Node(int s, int e, int c) {
+  			this.s = s;
+  			this.e = e;
+  			this.c = c;
+  		}
+	  }
+}
+
+```