이지영: [BOJ] 1647 도시 분할 계획_240917

BOJ/1000-10000번/JY_1647.java

@@ -0,0 +1,86 @@
+package day0917;
+
+import java.util.*;
+import java.io.*;
+
+public class JY_1647 {
+
+	static int N, M;
+	static int[] parents;
+	static List<Edge> eList;
+	static class Edge implements Comparable<Edge>{
+		int n1, n2, cost;
+		public Edge(int n1, int n2, int cost) {
+			this.n1 = n1;
+			this.n2 = n2;
+			this.cost = cost;
+		}
+		@Override
+		public int compareTo(Edge other) {
+			return this.cost - other.cost;
+		}
+		@Override
+		public String toString() {
+			return "("+this.n1+","+this.n2+"):"+this.cost; 
+		}
+	}
+
+	public static void main(String[] args) throws IOException {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		StringTokenizer st = new StringTokenizer(br.readLine());
+
+		N = Integer.parseInt(st.nextToken());
+		M = Integer.parseInt(st.nextToken());
+		eList = new ArrayList<>();
+		for(int i=0; i<M; i++) {
+			st = new StringTokenizer(br.readLine());
+			int n1 = Integer.parseInt(st.nextToken());
+			int n2 = Integer.parseInt(st.nextToken());
+			int cost = Integer.parseInt(st.nextToken());
+
+			eList.add(new Edge(n1, n2, cost));
+		}
+		// 엣지 정렬
+		Collections.sort(eList);
+//		System.out.println(eList);
+
+		// 부모 초기화(자기자신으로)
+		parents = new int[N+1];
+		for(int i=1; i<N+1; i++) {
+			parents[i] = i;
+		}
+
+		List<Edge> g = new ArrayList<>();
+		// 엣지 반복
+		for(Edge e: eList) {
+			// 부모가 같지 않으면 union
+			if(find(e.n1) != find(e.n2)) {
+				union(e.n1, e.n2);
+				g.add(e);
+			}
+		}
+		int dist = 0;
+		// 마지막 엣지 제거
+		for(int i=0; i<g.size()-1; i++) {
+			dist += g.get(i).cost;
+		}
+		System.out.println(dist);
+
+
+
+	}
+	public static int find(int x) {
+		if(parents[x] != x) {
+			parents[x] = find(parents[x]);
+		}
+		return parents[x];
+	}
+	public static void union(int a, int b) {
+		int pa = find(a);
+		int pb = find(b);
+		if(pa != pb) {
+			parents[pb] = pa;
+		}
+	}
+
+}