Array and String Manipulation Problems

case 1 : Reverse an array using another array

class Main {
    public static void main(String[] args) {
        int [] num = {10,11,12,13,14,15,16};
        System.out.println("Original Array :");
         for(int i=0;i<num.length;i++){
            System.out.print(num[i]+"  ");
        }
        //Create a result array to hold the required values, having the same length as num.
        int [] result = new int[num.length];

        // reverse the array here
        for(int i=num.length-1,j=0;i>=0;i--){
           result[j++]=num[i]; 
        }
        System.out.println();
        System.out.println("Reversed  Array :");
        // print the resultant array 
        for(int i=0;i<result.length;i++){
            System.out.print(result[i]+"  ");
        }
    }
}

case 2 : Reverse an array in-place without extra space

• A palindrome number is a number which remains the same when it is reversed.

class Main {
    public static void main(String[] args) {
        int [] num = {10,11,12,13,14,15,16};
        System.out.println("Original Array :");
         for(int i=0;i<num.length;i++){
            System.out.print(num[i]+"  ");
        }
        System.out.println();
        int left =0;
        int right = num.length-1;
        while(left < right){
            num[left] = (num[left]+num[right])-(num[right]=num[left]);
            left++; right--;
        }
        System.out.println("Reversed Array :");
         for(int i=0;i<num.length;i++){
            System.out.print(num[i]+"  ");
        }
    }   

    }

case 3 : Check whether the given string is a palindrome or not

class Main {
    public static void main(String[] args) {
     String str = "abcdcba";
     int left =0;
     int right=str.length()-1;
     boolean flag = true;
     while(left < right){
         if(str.charAt(left)!=str.charAt(right)){
             flag=false;
             break;
         }
         left++; right--;
     }
     if(flag==true){
         System.out.println(str+" is palindrome number");
     }
     else{
         System.out.println(str+" is not palindrome number");
     }
    }
}