[20250327] BOJ / G2 / Secret Milk Pipes / 권혁준

Author: oncsr

khj20006/202503/27 BOJ G2 Secret Milk Pipes.md

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+```java
+
+import java.util.*;
+import java.io.*;
+
+class Main {
+	
+	// IO field
+	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	static StringTokenizer st = new StringTokenizer("");
+
+	static void nextLine() throws Exception {st = new StringTokenizer(br.readLine());}
+	static String nextToken() throws Exception {
+		while(!st.hasMoreTokens()) nextLine();
+		return st.nextToken();
+	}
+	static int nextInt() throws Exception { return Integer.parseInt(nextToken()); }
+	static long nextLong() throws Exception { return Long.parseLong(nextToken()); }
+	static double nextDouble() throws Exception { return Double.parseDouble(nextToken()); }
+	static void bwEnd() throws Exception {bw.flush();bw.close();}
+	
+	// Additional field
+	
+	static int W, P;
+	static int[][] Edges;
+	
+	static List<int[]>[] V;
+	static int[] r;
+	
+	static int f(int x) {return x==r[x] ? x : (r[x]=f(r[x]));}
+	
+	public static void main(String[] args) throws Exception {
+			
+		ready();
+		solve();
+	
+		bwEnd();
+		
+	}
+	
+	static void ready() throws Exception{
+		
+		W = nextInt();
+		P = nextInt();
+		Edges = new int[P][3];
+		for(int i=0;i<P;i++) for(int j=0;j<3;j++) Edges[i][j] = nextInt();
+		
+		V = new List[W+1];
+		r = new int[W+1];
+		for(int i=1;i<=W;i++) {
+			V[i] = new ArrayList<>();
+			r[i] = i;
+		}
+		
+	}
+	
+	static void solve() throws Exception{
+
+		
+		Arrays.sort(Edges, (a,b) -> a[2]-b[2]);
+		
+		int mst = 0;
+		boolean[] used = new boolean[P];
+		for(int i=0;i<P;i++) {
+			int[] e = Edges[i];
+			int a = e[0], b = e[1], c = e[2];
+			int x = f(a), y = f(b);
+			if(x == y) continue;
+			mst += c;
+			V[a].add(new int[] {b,c});
+			V[b].add(new int[] {a,c});
+			r[x] = y;
+			used[i] = true;
+		}
+		
+		int min = (int)1e9;
+		for(int i=0;i<P;i++) if(!used[i]) {
+			int[] e = Edges[i];
+			int a = e[0], b = e[1], c = e[2];
+			
+			Queue<int[]> Q = new LinkedList<>();
+			boolean[] vis = new boolean[W+1];
+			
+			Q.offer(new int[] {a,0});
+			vis[a] = true;
+			while(!Q.isEmpty()) {
+				int[] now = Q.poll();
+				int n = now[0], t = now[1];
+				if(n == b) {
+					min = Math.min(min, c-t);
+					break;
+				}
+				for(int[] j:V[n]) if(!vis[j[0]]) {
+					vis[j[0]] = true;
+					Q.offer(new int[] {j[0],Math.max(t, j[1])});
+				}
+			}
+			
+		}
+		bw.write((mst+min)+"\n");
+	}
+	
+}
+
+```