BOJ_1939 : 중량제한

Author: spring0913

week5/BOJ_1939(중량제한).java

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+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static int N;
+    public static List<List<int[]>> graph;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        N = Integer.parseInt(st.nextToken());
+        int M = Integer.parseInt(st.nextToken());
+        graph = new ArrayList<>();
+        for (int i = 0; i <= N; i++) {
+            graph.add(new ArrayList<>());
+        }
+        int max = 0;
+        int min = Integer.MAX_VALUE;
+        for (int i = 0; i < M; i++) {
+            st = new StringTokenizer(br.readLine());
+            int A = Integer.parseInt(st.nextToken());
+            int B = Integer.parseInt(st.nextToken());
+            int C = Integer.parseInt(st.nextToken());
+            graph.get(A).add(new int[]{B, C});
+            graph.get(B).add(new int[]{A, C});
+            max = Math.max(max, C);
+            min = Math.min(min, C);
+        }
+        st = new StringTokenizer(br.readLine());
+        int start = Integer.parseInt(st.nextToken());
+        int end = Integer.parseInt(st.nextToken());
+
+        int left = min;
+        int right = max;
+        int answer = left;
+        while (left <= right) {
+            int mid = (left + right) / 2;
+            if (!checkPathWeight(start, end, mid)) {
+                right = mid - 1;
+            } else {
+                answer = Math.max(answer, mid);
+                left = mid + 1;
+            }
+        }
+        System.out.println(answer);
+    }
+
+    public static boolean checkPathWeight(int start, int end, int weight) {
+        boolean[] visited = new boolean[N + 1];
+        Queue<Integer> q = new LinkedList<>();
+        q.offer(start);
+        while (!q.isEmpty()) {
+            int v = q.poll();
+            if (v == end) {
+                return true;
+            }
+            List<int[]> list = graph.get(v);
+            for (int i = 0; i < list.size(); i++) {
+                int[] edge = list.get(i);
+                int vertex = edge[0];
+                if (edge[1] > 0 && edge[1] >= weight && !visited[vertex]) {
+                    visited[vertex] = true;
+                    q.offer(vertex);
+                }
+            }
+        }
+        return false;
+    }
+}