BOJ_4195 : 친구 네트워크

Author: spring0913

week8/BOJ_4195(친구 네트워크).java

@@ -0,0 +1,60 @@
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static Map<String, Integer> friendIndex;
+    public static int[] parent;
+    public static int[] count;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int T = Integer.parseInt(br.readLine());
+        StringBuilder sb = new StringBuilder();
+        for(int t=0; t<T; t++) {
+            int F = Integer.parseInt(br.readLine());
+            friendIndex = new HashMap<>();
+            count = new int[F*2];
+            parent = new int[F*2];
+            for(int i=1; i<F*2; i++) {
+                parent[i] = i;
+            }
+            int num = 0;
+            for(int i=0; i<F; i++) {
+                StringTokenizer st = new StringTokenizer(br.readLine());
+                String friend1 = st.nextToken();
+                String friend2 = st.nextToken();
+                if(!friendIndex.containsKey(friend1)) {
+                    count[num] = 1;
+                    friendIndex.put(friend1, num++);
+                }
+                if(!friendIndex.containsKey(friend2)) {
+                    count[num] = 1;
+                    friendIndex.put(friend2, num++);
+                }
+                int x = find(friendIndex.get(friend1));
+                int y = find(friendIndex.get(friend2));
+                union(x, y);
+                sb.append(count[x]).append('\n');
+            }
+        }
+        System.out.print(sb);
+    }
+
+    public static int find(int x) {
+        if(parent[x] == x) {
+            return x;
+        }
+        parent[x] = find(parent[x]);
+        return parent[x];
+    }
+    public static void union(int x, int y) {
+        x = find(x);
+        y = find(y);
+        if(x == y) {
+            return;
+        }
+        parent[y] = x;
+        count[x] += count[y];
+    }
+}