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  1. import java.util.*; 
  2.  
  3. import java.io.*;
  4.  
  5. public class Main { 
  6.  
  7. public static void main(String[]args){ 
  8.  
  9. FastReader in=new FastReader(); 
  10.  
  11. int n=in.nextInt(); 
  12.  
  13. int m=in.nextInt(); 
  14.  
  15. int[]x=new int[n]; 
  16.  
  17. for(int i=0;i<x.length;i++){ 
  18.  
  19. x[i]=in.nextInt();
  20.  
  21.  } 
  22.  
  23. List <Integer> [] g=new List[n];
  24.  
  25.  for(int i=0;i<g.length;i++){ 
  26.  
  27.   g[i]=new ArrayList();
  28.  
  29.  } 
  30.  
  31. boolean [] vis=new boolean[n]; 
  32.  
  33. int e=n-1; 
  34.  
  35. while(e-->0){ 
  36.  
  37. int a=in.nextInt()-1;
  38.  
  39.  int b=in.nextInt()-1; 
  40.  
  41. g[a].add(b); 
  42.  
  43. g[b].add(a); 
  44.  
  45. } 
  46.  
  47. Stack<Integer> s=new Stack(); 
  48.  
  49. s.push(0); 
  50.  
  51. vis[0]=true; 
  52.  
  53. int count=0; 
  54.  
  55. while(!s.isEmpty()){ 
  56.  
  57. int p=s.pop(); 
  58.  
  59. boolean t=true;
  60.  
  61. for(int y=0;y<g[p].size();y++){ 
  62.  
  63. int c=g[p].get(y); 
  64.  
  65. if(!vis[c]){ 
  66.  
  67. t=false;
  68.  
  69. if(x[c]>0){ 
  70.  
  71. if(!(x[p]+1>m)){ 
  72.  
  73. s.push(c); x[c]=x[p]+1; 
  74.  
  75. } 
  76.  
  77. } 
  78.  
  79. else
  80.    s.push(c); 
  81.  
  82. vis[c]=true; 
  83.  
  84. } 
  85.  
  86. } 
  87.  
  88. if(t){
  89.  
  90. count++; 
  91.  
  92. } 
  93.  
  94. } 
  95.  
  96.  
  97. System.out.println(count);
  98.  
  99.  } 
  100.  
  101.  
  102. } 
  103.  
  104.  
  105. class FastReader
  106.     {
  107.         BufferedReader br;
  108.         StringTokenizer st;
  109.  
  110.         public FastReader()
  111.         {
  112.             br = new BufferedReader(new
  113.                      InputStreamReader(System.in));
  114.         }
  115.  
  116.         String next()
  117.         {
  118.             while (st == null || !st.hasMoreElements())
  119.             {
  120.                 try
  121.                 {
  122.                     st = new StringTokenizer(br.readLine());
  123.                 }
  124.                 catch (IOException  e)
  125.                 {
  126.                     e.printStackTrace();
  127.                 }
  128.             }
  129.             return st.nextToken();
  130.         }
  131.  
  132.         int nextInt()
  133.         {
  134.             return Integer.parseInt(next());
  135.         }
  136.  
  137.         long nextLong()
  138.         {
  139.             return Long.parseLong(next());
  140.         }
  141.  
  142.         double nextDouble()
  143.         {
  144.             return Double.parseDouble(next());
  145.         }
  146.  
  147.         String nextLine()
  148.         {
  149.             String str = "";
  150.             try
  151.             {
  152.                 str = br.readLine();
  153.             }
  154.             catch (IOException e)
  155.             {
  156.                 e.printStackTrace();
  157.             }
  158.             return str;
  159.         }
  160. }
Runtime error #stdin #stdout #stderr 0.08s 51268KB
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Standard input is empty
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Standard output is empty
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Exception in thread "main" java.lang.NullPointerException
	at java.base/java.util.StringTokenizer.<init>(StringTokenizer.java:199)
	at java.base/java.util.StringTokenizer.<init>(StringTokenizer.java:236)
	at FastReader.next(Main.java:122)
	at FastReader.nextInt(Main.java:134)
	at Main.main(Main.java:11)
https://ideone.com/65ehyo
language:
Java (HotSpot 12)
created:
2 years ago
visibility:
secret

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