DSA

/*

Reverse a string without affecting special characters?
Primary Example ->
Input:   str = "a,b$c"
Output:  str = "c,b$a"
Non-special characters: a-zA-Z0-9
Secondary Example ->
Input:   str = "A4b,c,d0e!$" "A0b,c,d4e!$"
Output:  str = "e0d,c,b4A!$" 
*/

import java.util.regex.*; 
public class MyClass {
    public static void main(String args[]) {
        final String s1= "a,b$c";
        final String s2= "A4b,c,d0e!$";
        
        System.out.println(reverseNonSpecialCharacter(s1));
        System.out.println(reverseNonSpecialCharacter(s2));
    }
    
    public static String reverseNonSpecialCharacter(final String str){
        
        char strArray[] = str.toCharArray();
        String pattern = "^[a-zA-Z0-9]*$";
        Pattern p = Pattern.compile(pattern);
        int left = 0;
        int right = str.length()-1;
        
        while(left<right){
            while(left <str.length()-1 && !p.matcher(""+strArray[left++]).matches());
            
            while(right >0 && !p.matcher(""+strArray[right--]).matches());
            
            char temp = strArray[left];
            strArray[left] = strArray[right];
            strArray[right]= temp;
            
            left++;
            right--;
            
        }
        
        return new String(strArray);
    }
}



----------------------


/*
Write a method/function which provides nth number in Fibonacci series? 
Fib(0) = 0, Fib(1)=1, Fib(2)=1, Fib(3)=2, Fib(4)=3, Fib(5)=5, Fib(6)=8 and so on...
E.g. Fibonacci series Fib(5) = Fib(4) + Fib(3) = 3 + 2 = 5

*/

import java.util.regex.*; 
public class MyClass {
    public static void main(String args[]) {
        int N = 5;
        System.out.println(getFibbo(N));
    }
    
    public static int getFibbo(int N){
        int fibbo[] = new int[N+1];
        fibbo[0]=0;
        fibbo[1]=1;
        fibbo[2]=1;
        
        for(int i=3;i<=N;i++){
            fibbo[i]=fibbo[i-1]+fibbo[i-2];
        }
        
        return fibbo[N];
        
    }
}

------------------------

/*
input.add("+91-9876543210");
input.add("9876 543 210");
input.add("02269876543");
input.add("09876543210");
input.add("9876");
input.add("#108");
input.add("78654332");
input.add("56786 54332");
input.add("08765432190");
input.add("+91-7654321890");
input.add("0145243567");
input.add("9876543201");
input.add("+91-6789123450");
input.add("02298765432");
input.add("81234-56789");
input.add("919876543012");
input.add("+91-98765 43102");

*/

import java.util.*; 
public class MyClass {
    public static void main(String args[]) {
        List<String> input =  new ArrayList<>();
        input.add("+91-9876543210");
        input.add("9876 543 210");
        input.add("02269876543");
        input.add("09876543210");
        input.add("9876");
        input.add("#108");
        input.add("78654332");
        input.add("56786 54332");
        input.add("08765432190");
        input.add("+91-7654321890");
        input.add("0145243567");
        input.add("9876543201");
        input.add("+91-6789123450");
        input.add("02298765432");
        input.add("81234-56789");
        input.add("919876543012");
        input.add("+91-98765 43102");

        List<String> results = getFilteredList(input);
        for(String result :results)
            System.out.println(result);
    }
    
    public static List<String> getFilteredList(List<String> input){
        
        Iterator<String> iterator = input.iterator();
        while(iterator.hasNext()){
            final String phone = iterator.next();
            final String processNumber = processInput(phone);
        
            int phoneNumberLength = processNumber.length();
            
            if(phoneNumberLength<10){
                iterator.remove();
                continue;
            }
            boolean isValid = false;
            if(phoneNumberLength == 11 && phone.charAt(0)=='0'){
                isValid=true;
            }
            else if(phoneNumberLength == 12 && phone.substring(0,2).equals("91")){
                isValid=true;
            }else if(phoneNumberLength==10){
                isValid=true;
            }
            
            if(!isValid){
                iterator.remove();
            }
            
        }
        
        return input;
    }
    
    public static String processInput(String phone){
        phone = phone.replaceAll("\\s+","");
        phone = phone.replaceAll("-","");
        phone = phone.replaceAll("+","");
        return phone;
    }
    
}