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  1.  
  2. /**
  3.  * In-place words reversal in a character array
  4.  * @author PRATEEK
  5.  */
  6. class ReverseWordsCharArray {
  7.  
  8. 	/**Reverse Words in an array
  9. 	 */
  10. 	private static void reverseWords(char[] str) {
  11. 		if(str==null || str.length==0)
  12. 			return ;
  13.  
  14. 		String temp = new String(str);
  15. 		int len = str.length, l=0,r=0;
  16.  
  17. 		//Reverse the input array
  18. 		reverseArr(str, 0, str.length-1);
  19.  
  20. 		while(r<len && str[r] == ' ') //Skip initial Spaces, if any
  21. 			r++;
  22.  
  23. 		while(r<len)
  24. 		{
  25. 			l=r; //l hold the start character of the word
  26. 			while(r== len-2 || (r<len-1 && str[r+1] != ' ')) //Get the last character of the word in r
  27. 				r++;
  28.  
  29. 			reverseArr(str,l,r++);
  30.  
  31. 			while(r<len && str[r] == ' ') //Find the next character using r
  32. 				r++;	
  33. 		}
  34. 		System.out.println(temp +" ----> " +new String(str));
  35. 	}
  36.  
  37.  
  38. 	/**
  39. 	 * Reverse the character array between i and j (inclusive)
  40. 	 */
  41. 	private static void reverseArr(char[] s,int i, int j) {
  42. 		int len=i+(j-i)/2;  //look carefully this line, when i is not 0
  43. 		for(;i<=len;i++,j--)
  44. 			swap(s,i,j);
  45. 	}
  46.  
  47. 	/**
  48. 	 * Swaps the ith and jth indices
  49. 	 */
  50. 	private static void swap(char[] arr,int i, int j) {
  51. 		char temp  = arr[i];
  52. 		arr[i] = arr[j];
  53. 		arr[j]=temp;
  54. 	}
  55.  
  56. 	public static void main(String[] args) {
  57. 		String s1 = "  Coding    Recipes is Super   Cool  ";
  58. 		String s2 = "I live to code";
  59. 		String s3 = "Recursion is Recursion";
  60. 		//reverseWords1(s.toCharArray());
  61. 		reverseWords(s1.toCharArray());
  62. 		reverseWords(s2.toCharArray());
  63. 		reverseWords(s3.toCharArray());
  64. 		reverseWords("   ".toCharArray());
  65. 		reverseWords(null);
  66. 	}
  67. }
  68.  
Success #stdin #stdout 0.08s 380160KB
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  Coding    Recipes is Super   Cool   ---->   Cool   Super is Recipes    Coding  
I live to code ----> code to live I
Recursion is Recursion ----> Recursion is Recursion
    ---->
https://ideone.com/uhGnlH
Reverse Words in a character array
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

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