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Reverse words in a sentence
  • Posted: 7 years ago
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  • answers (1)
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Write a function to reverse the order of a sentence word by word without using any other data
structure. \( E.g \), if the input is `Algoqueue is the best website', the result will be `website best the is Algoqueue'.


Posted Answers

  • Posted: 7 years ago
  • Updated: 7 years ago
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  • Edit

< Using split function >


  • Split the whole sentence word by word and store them in a String array.
  • Iterate through the array from end to beginning and add each word to the result.

public static void revSentenceWordByWord(String input){

     /* Split word by word */
     string[] word =  input.split(" ");
     StringBuilder result = new StringBuilder();
     /* Iterate from end to beginning */
     for(int i = word.length - 1; i >= 0 ; i--)
        result.append(word[i]);
        result.append(" ");

     System.out.println(result.toString());

 }



< Without using split function >

  • Reverse the given string (the whole sentence).
  • Reverse each word in the string.

public static char[] revSentenceWordByWord(char[] input){

     int beginIndex = 0;
     int endIndex = input.length - 1;
     if (endIndex > 1){

        /* Reverse the whole sentence */
        input = reverseString(input, 0, endIndex);

        /* Reverse each word in the reversed sentence */
        for (endIndex = 0; endIndex  < = input.length; endIndex++){
            if (endIndex == input.length || input[endIndex] == ' '){
                input = reverseString(input, beginIndex, endIndex - 1);
                beginIndex = endIndex + 1;
            }
        }
     }
     return input;
 }

 public static char[] reverseString(char[] input, int beginIndex, int endIndex){

     char temp;
     while(beginIndex  <  endIndex){

         temp = input[beginIndex];
         input[beginIndex++] = input[endIndex];
         input[endIndex--] = temp;
     }
     return input;
 }
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