#### Two Pointers

s
A
a
```package com.thealgorithms.others;

import java.util.Arrays;

/**
* The two pointer technique is a useful tool to utilize when searching for
* pairs in a sorted array.
*
* <p>
*/
class TwoPointers {

public static void main(String[] args) {
int[] arr = { 10, 20, 35, 50, 75, 80 };
int key = 70;
assert isPairedSum(arr, key);
/* 20 + 60 == 70 */

arr = new int[] { 1, 2, 3, 4, 5, 6, 7 };
key = 13;
assert isPairedSum(arr, key);
/* 6 + 7 == 13 */

key = 14;
assert !isPairedSum(arr, key);
}

/**
* Given a sorted array arr (sorted in ascending order). Find if there
* exists any pair of elements such that their sum is equal to key.
*
* @param arr the array contains elements
* @param key the number to search
* @return {@code true} if there exists a pair of elements, {@code false}
* otherwise.
*/
private static boolean isPairedSum(int[] arr, int key) {
/* array sorting is necessary for this algorithm to function correctly */
Arrays.sort(arr);
int i = 0;
/* index of first element */
int j = arr.length - 1;
/* index of last element */

while (i < j) {
if (arr[i] + arr[j] == key) {
return true;
} else if (arr[i] + arr[j] < key) {
i++;
} else {
j--;
}
}
return false;
}
}
```