Given a string str consisting of a sentence, the task is to reverse every word in the sentence except the first and last characters of the word.

Examples:  

Input: str = “geeks for geeks” 
Output: gkees for gkees

Input: str = “this is a string” 
Output: tihs is a snirtg  

Approach:

Use strtok() to split the string into words. Now each word uses two pointers, i and j point to the penultimate character and the penultimate character of the string, respectively. Swap these characters, then increase i and decrease j. Repeat these steps when i <j. The following is the implementation of the above method:

// Java implementation of the above approach
class GFG
{
	
// Function to reverse the given word except
// the first and the last character
static String reverseWord(String str)
{
	int len = str.length();
	
	// Pointer to the second character
	// of the string
	int i = 1;

	// Pointer to the second last
	// character of the string
	int j = str.length() - 2;
	
	char[] strchar = str.toCharArray();

	while (i < j)
	{

		// Swap str[i] and str[j]
		char temp = strchar[i];
		strchar[i] = strchar[j];
		strchar[j] = temp;
		i++;
		j--;
	}
	
	str = new String(strchar);
	return str;
}

// Function to reverse every word of the
// sentence except the first and the
// last character of the words
static void reverseWords(String str)
{
	String[] tok = str.split("\\s");

	// While there are words left
	for(String w:tok)
	{

		// Print the reversed word
		System.out.print(reverseWord(w) + " ");
	}
}

// Driver code
public static void main (String[] args)
{
	String str = "geeks for geeks";
	reverseWords(str);
}
}
	
// This code is contributed by AnkitRai01

Output: 

gkees for gkees