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  1. import java.util.*;
  2.  
  3. public class Main {
  4.  
  5.     public static void findWaysToReachNodes(int n, int[][] edges) {
  6.         List<List<Integer>> graph = new ArrayList<>();
  7.         for (int i = 0; i <= n; i++) {
  8.             graph.add(new ArrayList<>());
  9.         }
  10.  
  11.         for (int[] edge : edges) {
  12.             graph.get(edge[0]).add(edge[1]);
  13.             graph.get(edge[1]).add(edge[0]);
  14.         }
  15.  
  16.         Queue<Integer> queue = new LinkedList<>();
  17.         int[] visited = new int[n + 1];
  18.         int[] ways = new int[n + 1];
  19.         int[] level = new int[n + 1];
  20.  
  21.         queue.add(1);
  22.         visited[1] = 1;
  23.         ways[1] = 1;
  24.         level[1] = 0;
  25.  
  26.         while (!queue.isEmpty()) {
  27.             int node = queue.poll();
  28.             System.out.println("Node: " + node + ", Ways: " + ways[node]);
  29.  
  30.             for (int neighbor : graph.get(node)) {
  31.                 if (visited[neighbor] == 0) {
  32.                     queue.add(neighbor);
  33.                     visited[neighbor] = 1;
  34.                     level[neighbor] = level[node] + 1;
  35.                     ways[neighbor] = ways[node];
  36.                 } else if (level[neighbor] == level[node] + 1) {
  37.                     ways[neighbor] += ways[node];
  38.                 }
  39.             }
  40.         }
  41.     }
  42.  
  43.     public static void main(String[] args) {
  44.         int n = 5;
  45.         int[][] edges = {
  46.             {1, 2}, {1, 3}, {2, 4}, {3, 4}, {4, 5}
  47.         };
  48.  
  49.         findWaysToReachNodes(n, edges);
  50.     }
  51. }
  52.  
Success #stdin #stdout 0.16s 55504KB
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stdin
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Standard input is empty
stdout
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Node: 1, Ways: 1
Node: 2, Ways: 1
Node: 3, Ways: 1
Node: 4, Ways: 2
Node: 5, Ways: 2
https://ideone.com/uowQcy
language:
Java (HotSpot 12)
created:
285 days ago
visibility:
public

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