a_114_PairSum2.java

import java.util.ArrayList;

public class a_114_PairSum2 {
    // 2 Pointer Approach 
    public static boolean pairSum2(ArrayList<Integer> list , int target){

        int bp = -1 ;
        int n = list.size() ;

        for(int i=0; i<list.size() ; i++){
            if(list.get(i) > list.get(i+1) ){  // Breaking Points
                bp = i ;
                break ;
            }
        }

        int lp = bp + 1 ;   // Smallest Index
        int rp = bp ;       // Largest Index 

        while(lp != rp){
            // Case 1
            if(list.get(lp) + list.get(rp) == target){
                return true ;
            }
            // Case 2 
            if(list.get(lp) + list.get(rp) < target){
                lp = (lp + 1) % n ;
            }
            else{  // Case 3
                rp = (n + rp - 1) % n ;
            }

        }

        return false ;
    }
    public static void main(String[] args) {
        ArrayList<Integer> list = new ArrayList<>() ;
          // 11, 15, 6, 8, 9, 10  --> Sorted and Rotated List 
        list.add(11) ;
        list.add(15) ;
        list.add(6) ;
        list.add(8) ;
        list.add(9) ;
        list.add(10) ;
        int target = 160;


        System.out.println( pairSum2(list, target) );
    }
}