[20251014] BOJ / G4 / 도시 분할 계획 / 이인희

LiiNi-coder/202510/14 BOJ 도시 분할 계획.md

@@ -0,0 +1,80 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    private static int N, M;
+    private static int[] Parent;
+    private static List<Edge> Edges = new ArrayList<>();
+
+    private static class Edge implements Comparable<Edge> {
+        int from, to, cost;
+        Edge(int from, int to, int cost) {
+            this.from = from;
+            this.to = to;
+            this.cost = cost;
+        }
+        @Override
+        public int compareTo(Edge e) {
+            return this.cost - e.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());
+        Parent = new int[N+1];
+
+
+        for(int i=1; i<=N; i++){
+            Parent[i] = i;
+        }
+
+        for(int i=0; i<M; i++){
+            st = new StringTokenizer(br.readLine());
+            int from = Integer.parseInt(st.nextToken());
+            int to = Integer.parseInt(st.nextToken());
+            int cost = Integer.parseInt(st.nextToken());
+            Edges.add(new Edge(from, to,cost));
+        }
+
+        Collections.sort(Edges);
+        int answer = 0;
+        int countOfEdge = 0;
+
+        for(Edge e : Edges){
+            if(countOfEdge == N-2)
+                break;
+            if(union(e.from,e.to)){
+                answer += e.cost;
+                countOfEdge++;
+            }
+        }
+
+        System.out.println(answer);
+        br.close();
+    }
+
+    private static boolean union(int a, int b){
+        a = find(a);
+        b = find(b);
+        if(a==b)
+            return false;
+        Parent[b] = a;
+        return true;
+    }
+
+    private static int find(int x){
+        if(Parent[x]==x){
+            return x;
+
+        }
+        Parent[x] = find(Parent[x]);
+        return Parent[x];
+    }
+
+}
+
+```