Question

For a given string S, the function change (n, m) replaces all 'n' with 'm' in string S. For example, if S = "alopecia", change (a, b) will give the string "blopecib". You need to find the minimum number of uses of change (n, m) such that the string S forms a palindrome. ​ I'm looking for a O(length(S)) solution. Preferably JAVA.

Answer 1

// Code to copy

// Create class 
public class MinChange
{
    // create method to find the minimum number
    // character change required
    public static void minchange(char[] s)
    {
        // Finding the length of the string  
        int n = s.length;  
  
        // To store the number of replacement operations  
        int count = 0;
        for(int i=0;i<n/2;i++) 
            { 
                
                // If the characters at location i and n-i-1 are same then  
                // no change is needed
                if(s[i]== s[n-i-1])  
                    continue; 
                
                // Counting one change operation  
                count+= 1; 

                // change(n,m) function part
                // Changing the character with higher  
                // ascii value with lower ascii value  
                if(s[i]<s[n-i-1])  
                    s[n-i-1]= s[i] ; 
                else
                    s[i]= s[n-i-1] ; 
            }
        System.out.println("Minimum characters to be replaced = "+count);
        System.out.println(s);
    }

    // create main method (driver code)
    public static void main(String[] args)
    {
        String s = "ceeks";
        char[] schar = s.toCharArray();
        minchange(schar);  
    }
}

// screenshot of the code

// screenshot of the output

// In case of any query, you can ask in comment

// thanks