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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 void main(final String[] args) {
  11. 		System.out.println("Please enter two numbers which have no more than 50 digits: ");
  12. 		final Scanner s = new Scanner(System.in);
  13. 		final String x = s.next();
  14. 		final String y = s.next();
  15.  
  16. 		System.out.println("Calculating: (" + x + " + " + y + ")");
  17.  
  18. 		//The arrays come back in ascending order of magnitude. See method comment.
  19. 		final int[] xDigits = stringToIntArray(x);
  20. 		final int[] yDigits = stringToIntArray(y);
  21. 		final int[] result = new int[51]; //This array will only ever be 51 in size at most
  22. 		int carryOver = 0;
  23.  
  24. 		//Add up each individual digit and process any carry over
  25. 		for (int i = 0; i < 50; i++) {
  26. 			final int j = xDigits[i] + yDigits[i] + carryOver;
  27. 			if( j > 9 ) {
  28. 				result[i] = j % 10;
  29. 				carryOver = 1; //Since we're adding each individual digit, the only possible carry over is 1.
  30. 			}
  31. 			else {
  32. 				result[i] = j;
  33. 				carryOver = 0; //No carry over in this case.
  34. 			}
  35. 		}
  36.  
  37. 		//We're now about to print the result, so reverse the array to get the descending order of magnitude
  38. 		reverseArray(result);
  39.  
  40. 		System.out.print("Result: ");
  41. 		//This print boolean is used to ignore any leading 0s.
  42.  
  43. 		//Use the boolean so that we do print trailing or middling 0s
  44. 		boolean print = false;
  45. 		for (final int i : result) {
  46. 			if( !print && i == 0 ) {
  47. 				continue;
  48. 			}
  49. 			else {
  50. 				print = true;
  51. 			}
  52. 			System.out.print(i);
  53. 		}
  54. 		s.close();
  55. 	}
  56.  
  57. 	private static void reverseArray(final int[] result) {
  58. 		for(int i = 0; i < result.length/2; i++) {
  59. 			final int temp = result[i];
  60. 			result[i] = result[result.length - i - 1];
  61. 			result[result.length - i - 1] = temp;
  62. 		}
  63. 	}
  64.  
  65. 	/**
  66. 	 * Will assume the String is a number and return an int[] that contains
  67. 	 * the digits form the number in ascending magnitude order left to write.
  68. 	 * i.e.:
  69. 	 * 		Input:		12345
  70. 	 * 		Becomes:	{5,4,3,2,1}
  71. 	 */
  72. 	public static int[] stringToIntArray(final String n) {
  73. 		final char[] charArray = n.toCharArray();
  74. 		final int[] result = new int[50];
  75.  
  76. 		int resultIndex = 0;
  77. 		for (int i = (charArray.length-1); i >=0 ; i--) {
  78. 			result[resultIndex] = Integer.parseInt( "" + charArray[i] );
  79. 			resultIndex++;
  80. 		}
  81.  
  82. 		return result;
  83. 	}
  84. }
Runtime error #stdin #stdout #stderr 0.11s 380672KB
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stdin
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Standard input is empty
stdout
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Please enter two numbers which have no more than 50 digits:
stderr
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Exception in thread "main" java.util.NoSuchElementException
	at java.util.Scanner.throwFor(Scanner.java:907)
	at java.util.Scanner.next(Scanner.java:1416)
	at Ideone.main(Main.java:13)
https://ideone.com/IU1Yes
language:
Java (HotSpot 12)
created:
11 years ago
visibility:
public

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