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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static class BDD {
  11. 		static final BDD TRUE = new BDD();
  12. 		static final BDD FALSE = new BDD();
  13. 		BDD trueC, falseC;
  14. 		String v;
  15.  
  16. 		boolean isDAG(){
  17. 			return isDAG(new HashSet<BDD>());
  18. 		}
  19.  
  20. 		boolean isDAG(HashSet<BDD> p) {
  21. 	    	if (p.contains(this)) {
  22. 		    	return false;
  23. 	    	}
  24. 	    	p.add(this);
  25. 	    	boolean ret = (trueC == null || trueC.isDAG(p)) && (falseC == null || falseC.isDAG(p));
  26. 	    	p.remove(this);
  27. 	    	return ret;
  28. 		}
  29. 	}
  30.  
  31. 	public static void main (String[] args) throws java.lang.Exception
  32. 	{
  33. 		// b=TRUE <-- a <-- c
  34. 		// a is not the root of the DAG!
  35. 		BDD a = new BDD();
  36. 		BDD b = BDD.TRUE;
  37. 		BDD c = new BDD();
  38. 		c.trueC = a;
  39.  
  40. 		a.v = "a";
  41. 		c.v = "c";
  42. 		System.out.println("b=TRUE <-- a <-- c: failed? " + (a.isDAG() ? "yes" : "no"));
  43. 	}
  44. }
Success #stdin #stdout 0.1s 320576KB
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Standard input is empty
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b=TRUE <-- a <-- c: failed? yes
https://ideone.com/3uvNOr
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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