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  1. import java.util.*;
  2. import java.util.regex.*;
  3.  
  4. class Ideone
  5. {
  6.     static Pattern pattern = Pattern.compile("[a-zA-Z0-9]{0,100}<(/?)([ab])>");
  7.  
  8.     static void test(String str)
  9.     {
  10.         System.out.println(str);
  11.         LinkedList<String> elements = new LinkedList<String>();
  12.         elements.add("");
  13.  
  14.         Matcher matcher = pattern.matcher(str);
  15.         while (matcher.find())
  16.         {
  17.             if ("".equals(matcher.group(1)))
  18.             {
  19.                 switch (elements.getLast())
  20.                 {
  21.                 case "a": if ("b".equals(matcher.group(2))) break;
  22.                 case "b": System.out.println(0); return;
  23.                 }
  24.                 elements.add(matcher.group(2));
  25.             }
  26.             else if (!elements.removeLast().equals(matcher.group(2)))
  27.             {
  28.                 System.out.println(0);
  29.                 return;
  30.             }
  31.         }
  32.         System.out.println(elements.size() == 1 ? 1 : 0);
  33.     }
  34.  
  35.     public static void main(String[] args)
  36.     {
  37.         test("<a>ruby<b>php</b>python</a><a><b></b></a><a></a>");
  38.  
  39.         test("<a>ruby<b>php</b>python</a><a></b></a><a></a>");
  40.         test("<a>ruby<b>php</b>python</a><a><b></a><a></a>");
  41.         test("<a>ruby<b>php</b>python</a><a><b></b></a><a>");
  42.         test("vvvc<a>ruby<b>php</b>python</a><a><b></b></a><a></a>");
  43.     }
  44. }
Success #stdin #stdout 0.11s 320256KB
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stdin
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Standard input is empty
stdout
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<a>ruby<b>php</b>python</a><a><b></b></a><a></a>
1
<a>ruby<b>php</b>python</a><a></b></a><a></a>
0
<a>ruby<b>php</b>python</a><a><b></a><a></a>
0
<a>ruby<b>php</b>python</a><a><b></b></a><a>
0
vvvc<a>ruby<b>php</b>python</a><a><b></b></a><a></a>
1
https://ideone.com/5t4pMZ
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
secret

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