solved 부대복귀 - 131.21ms 198mb

Programmers/부대복귀/부대복귀_김훈민.java

@@ -0,0 +1,47 @@
+import java.util.*;
+
+class Solution {
+    static int[] visited;
+    static ArrayList<Integer>[] graph;
+    static int dest;
+    static Queue<Integer> queue = new LinkedList<>();
+    public int[] solution(int n, int[][] roads, int[] sources, int destination) {
+        visited = new int[n+1];
+        Arrays.fill(visited, Integer.MAX_VALUE);
+        graph = new ArrayList[n+1];
+        for(int i = 1; i < n+1; i++){
+            graph[i] = new ArrayList();
+        }
+        for(int[] road : roads){
+            graph[road[0]].add(road[1]);
+            graph[road[1]].add(road[0]);
+        }
+        bfs(destination);
+        int[] answer = new int[sources.length];
+        int cnt = 0;
+        for(int source : sources){
+            if(visited[source] == Integer.MAX_VALUE) answer[cnt++] = -1;
+            else answer[cnt++] = visited[source];
+        }
+        return answer;
+    }
+
+    static void bfs(int start){
+        queue.add(start);
+        visited[start] = 0;
+        int size = queue.size();
+        int time = 1;
+        while(!queue.isEmpty()){
+            for(int i = 0; i < size; i++){
+                int cur = queue.poll();
+                for(int next : graph[cur]){
+                    if(visited[next] != Integer.MAX_VALUE) continue;
+                    visited[next] = time;
+                    queue.add(next);
+                }
+            }
+            size = queue.size();
+            time++;
+        }
+    }
+}