가장 먼 노드 - level3

programmers/FarthestNode.java

@@ -0,0 +1,55 @@
+import java.util.*;
+
+class Solution {
+    private ArrayList<ArrayList<Integer>> list = new ArrayList<>();
+    private boolean visited[];
+    private int depth[];
+
+    public int solution(int n, int[][] edge) {
+        init(n,edge);
+
+        bfs(1);
+
+        Arrays.sort(depth);
+
+        int answer = 0;
+        int max = depth[n];
+        for(int i=n; i>=0; i--){
+            if(max != depth[i]) break;
+            answer++;
+        }
+        return answer;
+    }
+
+    public void bfs(int start){
+        Queue<Integer> queue = new LinkedList<>();
+        queue.add(start);
+        depth[start] = 1;
+        visited[start] = true;
+
+        while(!queue.isEmpty()){
+            int cur = queue.poll();
+
+            for(int vertex : list.get(cur)){
+                if(!visited[vertex]){
+                    queue.add(vertex);
+                    depth[vertex] = depth[cur]+1;
+                    visited[vertex] = true;
+                }
+            }
+        }
+    }
+
+    public void init(int n, int [][] edge){
+
+        for(int i=0; i<=n; i++) list.add(new ArrayList<>());
+
+        for(int i=0; i<edge.length; i++){
+            list.get(edge[i][0]).add(edge[i][1]);
+            list.get(edge[i][1]).add(edge[i][0]);
+        }
+
+        visited = new boolean[n+1];
+        depth = new int[n+1];
+    }
+}