[20251214] BOJ / P4 / 유럽여행 / 한종욱

Author: Ukj0ng

Ukj0ng/202512/14 BOJ P4 유럽여행.md

@@ -0,0 +1,100 @@
+```
+import java.io.*;
+import java.util.*;
+
+public class Main {
+    private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static PriorityQueue<Edge> edges;
+    private static int[] arr, uf, size;
+    private static int N, P, cost;
+
+    public static void main(String[] args) throws IOException {
+        init();
+        int answer = MST(cost);
+
+        bw.write(answer + "\n");
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static void init() throws IOException {
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        P = Integer.parseInt(st.nextToken());
+        cost = 1001;
+
+        arr = new int[N+1];
+        uf = new int[N+1];
+        size = new int[N+1];
+
+        for (int i = 1; i <= N; i++) {
+            arr[i] = Integer.parseInt(br.readLine());
+            cost = Math.min(cost, arr[i]);
+            uf[i] = i;
+            size[i] = 1;
+        }
+
+        edges = new PriorityQueue<>((o1, o2) -> Integer.compare(o1.w, o2.w));
+
+        for (int i = 0; i < P; i++) {
+            st = new StringTokenizer(br.readLine());
+            int s = Integer.parseInt(st.nextToken());
+            int e = Integer.parseInt(st.nextToken());
+            int l = Integer.parseInt(st.nextToken());
+
+            edges.add(new Edge(s, e, l*2 + arr[s] + arr[e]));
+        }
+    }
+
+    private static int MST(int cost) {
+        int count = 0;
+
+        while (count < N && !edges.isEmpty()) {
+            Edge edge = edges.poll();
+
+            int root1 = find(edge.u);
+            int root2 = find(edge.v);
+
+            if (root1 == root2) continue;
+            union(edge.u, edge.v);
+            cost += edge.w;
+            count++;
+        }
+
+        return cost;
+    }
+
+    private static void union(int x, int y) {
+        int X = find(x);
+        int Y = find(y);
+
+        if (size[X] < size[Y]) {
+            uf[X] = Y;
+            size[Y] += size[X];
+        } else {
+            uf[Y] = X;
+            size[X] += size[Y];
+        }
+    }
+
+    private static int find(int x) {
+        if (uf[x] == x) return x;
+
+        return uf[x] = find(uf[x]);
+    }
+
+    static class Edge {
+        int u;
+        int v;
+        int w;
+
+        public Edge(int u, int v, int w) {
+            this.u = u;
+            this.v = v;
+            this.w = w;
+        }
+    }
+}
+```