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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. import java.math.*;
  7.  
  8. /* Name of the class has to be "Main" only if the class is public. */
  9. class Ideone
  10. {
  11.     public static BigInteger fooBI2(int n) {
  12.         BigInteger[] vars = new BigInteger[3];
  13.         vars[0] = BigInteger.valueOf(1L);
  14.         vars[1] = BigInteger.valueOf(2L);
  15.         vars[2] = BigInteger.valueOf(4L);
  16.         for (int i = 3; i < n; i++) {
  17.             vars[i%3] = vars[0].add(vars[1]).add(vars[2]);
  18.         }
  19.         return vars[(n-1)%3].mod(BigInteger.valueOf((long) (Math.pow(10, 9) + 7)));
  20.     }
  21.  
  22.     public static int fooBI3(int n) {
  23.     	int p = 1000000007;
  24.         int[] vars = new int[3];
  25.         vars[0] = 1;
  26.         vars[1] = 2;
  27.         vars[2] = 4;
  28.         for (int i = 3; i < n; i++) {
  29.             vars[i%3] = ((vars[0] + vars[1])%p +vars[2])%p;
  30.         }
  31.         return vars[(n-1)%3];
  32.     }
  33.  
  34. 	public static void main (String[] args) throws java.lang.Exception
  35. 	{
  36. 		System.out.println("15: " + fooBI2(15) + "  " + fooBI3(15));
  37. 		System.out.println("20000: " + fooBI2(20000) + "  " + fooBI3(20000));
  38. 	}
  39. }
Success #stdin #stdout 0.2s 98640KB
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stdin
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15: 5768  5768
20000: 886919695  886919695
https://ideone.com/kx8lSO
language:
Java (HotSpot 12)
created:
3 years ago
visibility:
secret

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