twoSum Algorithm : How to improve this?

Question

I felt like doing an algorithm and found this problem on leetcode

Given an array of integers, find two numbers such that they add up to a specific target num

Answer 1

Here is an Efficient Solution.

Time Complexity - O(n) and Space Complexity - O(1)

Sol: Will take two-pointer(start_pointer and end_pointer). Initially start_pointer point at the first index and end_pointer point to the last.

Add both the element (sum = array[start_pointer] + array[last_pointer]. After that check, if the sum > target element or not. If yes decrease the end_pointer else increase start_pointer. If sum = target, means you got the indexes.

public int[] twoSum(int[] numbers, int target) {

    int[] arr = new int[2]; // to store result
    int sum=0;

    int start_pointer=0;     
    int end_pointer = (numbers.length)-1;

    while(start_pointer<=end_pointer){

        sum=numbers[start_pointer]+numbers[end_pointer]; 

        if(sum>target)
            end_pointer-=1;
        else if(sum