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  1. import java.util.*;
  2. import java.lang.*;
  3.  
  4. class Main
  5. {
  6. 	private static void printAllStringsOfLength(int len) {
  7. 		long start = System.nanoTime();
  8. 	    char[] guess = new char[len];
  9. 	    Arrays.fill(guess, 'a');
  10. 	    int totalGuesses = 0;
  11.  
  12. 	    do {
  13. 	        //System.out.println("Current guess:  " + new String(guess));
  14. 	    	totalGuesses++;
  15. 	        int incrementIndex = guess.length - 1;
  16. 	        while (incrementIndex >= 0) {
  17. 	            guess[incrementIndex]++;
  18. 	            if (guess[incrementIndex] > 'z') {
  19. 	                if (incrementIndex > 0) {
  20. 	                    guess[incrementIndex] = 'a';
  21. 	                }
  22. 	                incrementIndex--;
  23. 	            }
  24. 	            else {
  25. 	                break;
  26. 	            }
  27. 	        }
  28.  
  29. 	    } while (guess[0] <= 'z');
  30.  
  31. 	    long time = System.nanoTime() - start;
  32. 		System.out.printf("printAllStringsOfLength() yook %.3f seconds to generate %,d combinations%n", time / 1e9, totalGuesses);
  33. 	}
  34.  
  35. 	private static void alternatePrint(int len) {
  36. 		long start = System.nanoTime();
  37. 		int letters = 26;
  38. 		int count = len;
  39. 		int totalGuesses = 0;
  40. 		StringBuilder sb = new StringBuilder(count);
  41. 		int combinations = (int) Math.pow(letters, count);
  42. 		for (int i = 0; i < combinations; i++) {
  43. 		    sb.setLength(0);
  44. 		    for (int j = 0, i2 = i; j < count; j++, i2 /= letters)
  45. 		        sb.insert(0, (char) ('a' + i2 % letters));
  46. 		//  System.out.println(sb);
  47. 		    totalGuesses++;
  48. 		}
  49. 		long time = System.nanoTime() - start;
  50. 		System.out.printf("alternatePrint() took %.3f seconds to generate %,d combinations%n", time / 1e9, totalGuesses);
  51. 	}
  52.  
  53. 	public static void main(String[] args) {
  54. 		printAllStringsOfLength(5);
  55. 		alternatePrint(5);
  56. 	}
  57. }
Success #stdin #stdout 3.81s 212864KB
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Standard input is empty
stdout
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printAllStringsOfLength() yook 0.059 seconds to generate 11,881,376 combinations
alternatePrint() took 3.644 seconds to generate 11,881,376 combinations
https://ideone.com/zetH2
language:
Java (HotSpot 12)
created:
13 years ago
visibility:
public

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