{"id":9612,"date":"2022-09-12T08:00:40","date_gmt":"2022-09-12T08:00:40","guid":{"rendered":"https:\/\/www.prepbytes.com\/blog\/?p=9612"},"modified":"2022-10-03T04:00:23","modified_gmt":"2022-10-03T04:00:23","slug":"reverse-individual-words","status":"publish","type":"post","link":"https:\/\/prepbytes.com\/blog\/reverse-individual-words\/","title":{"rendered":"Reverse Individual Words"},"content":{"rendered":"

\"\"<\/p>\n

Problem Statment<\/h3>\n

You are given a string. This string contains many words that are space separated. You have to reverse each word in the string individually.<\/p>\n

Examples<\/strong><\/p>\n

The input string is \u201cHello and Welcome to PrepBytes\u201d.
\nSo, the output for this string should be \u201colleH dna emocleW ot setyBperP\u201d.<\/p>\n

Let us take another example. Say the input string is \u201cHello\u201d. So, the output for this is \u201colleH\u201d. Since there is only one word, we reverse it. Please note that there is no space after the last word in both the outputs.<\/p>\n

Constraints<\/strong><\/p>\n

The input string will only have 1 whitespace between the words. Also, for the output, you have to maintain the same.
\nIt is recommended not to use any predefined functions for reversing the strings<\/a> to solve the problem.<\/p>\n

Basic Approach<\/h3>\n

The primary approach is to get all the words in an ArrayList or vector of strings. Then, we can reverse each word and print them space-separated. This is shown below.<\/p>\n

\"\"<\/p>\n

The input string is as shown. We have a pointer at the first index of the input string. Since it is a character and not a whitespace, the pointer keeps moving forward and we keep adding the characters to a temporary string till the pointer encounters whitespace.<\/p>\n

\"\"<\/p>\n

As space is encountered, we insert the temporary string in our vector\/ArrayList. So, the same will happen for the next word as shown below.<\/p>\n

\"\"<\/p>\n

Now, the last word will not encounter a string. So, when the pointer reaches index = size of the input string, we will insert the last string into the vector\/ArrayList.<\/p>\n

\"\"<\/p>\n

Now that we have all the words with us, we reverse each word and add them with a space into the output string.
\nWhen we insert the last word, we will not insert space after it.<\/p>\n

Now, we only need to learn to reverse a string. So, let us discuss it.<\/p>\n

Reverse a Word<\/strong><\/p>\n

Consider the word shown below<\/p>\n

\"\"<\/p>\n

We have taken 2 pointers, low and high. The pointer low is at the index 0 and the pointer high is at the last index of the word. <\/p>\n

We will swap the characters at low and high and increment the low pointer and decrement the high pointer till low is less than high. This will reverse the word as shown below.<\/p>\n

\"\"<\/p>\n

Note: In Java, we will use StringBuilder (or StringBuffer) in place of Strings as Strings are immutable in Java, and reversing a String is an O(N2) operation in Java (since the same string does not get reversed and a new copy is created at every instance). On the other hand, reversing a StringBuilder is O(N) operation (reversing takes place within the same StringBuilder). In fact, reversing a String is not even possible in Java as for reversing a String, we need to change the characters of the already existing String and to change a character at a particular index of a String is not possible in Java (as there is no functionality to set a character at an index in a String in Java).
\nSo, when we use StringBuilder, we will simply append the characters of the word in reverse order so that a reversed word is formed. This can be seen in the code given below.<\/p>\n\t\t\t\t\t\t