package com.thealgorithms.others;
/**
* The two-pointer technique is a useful tool to utilize when searching for
* pairs in a sorted array.
*
* <p>
* Link: https://www.geeksforgeeks.org/two-pointers-technique/
*/
final class TwoPointers {
private TwoPointers() {
}
/**
* Given a sorted array arr (sorted in ascending order), find if there exists
* any pair of elements such that their sum is equal to the key.
*
* @param arr the array containing elements (must be sorted in ascending order)
* @param key the number to search
* @return {@code true} if there exists a pair of elements, {@code false} otherwise.
*/
public static boolean isPairedSum(int[] arr, int key) {
int i = 0; // index of the first element
int j = arr.length - 1; // index of the last element
while (i < j) {
int sum = arr[i] + arr[j];
if (sum == key) {
return true;
} else if (sum < key) {
i++;
} else {
j--;
}
}
return false;
}
}