Java Program to Find the closest pair from two sorted arrays

Given two sorted arrays and a number x, find the pair whose sum is closest to x and the pair has an element from each array.  We are given two arrays ar1[0…m-1] and ar2[0..n-1] and a number x, we need to find the pair ar1[i] + ar2[j] such that absolute value of (ar1[i] + ar2[j] – x) is minimum. Example:

Input:  ar1[] = {1, 4, 5, 7};
        ar2[] = {10, 20, 30, 40};
        x = 32      
Output:  1 and 30

Input:  ar1[] = {1, 4, 5, 7};
        ar2[] = {10, 20, 30, 40};
        x = 50      
Output:  7 and 40

Java

// Java program to find closest pair in an array
class ClosestPair {
    // ar1[0..m-1] and ar2[0..n-1] are two given sorted
    // arrays/ and x is given number. This function prints
    // the pair from both arrays such that the sum of the
    // pair is closest to x.
    void printClosest(int ar1[], int ar2[], int m, int n, int x)
    {
        // Initialize the diff between pair sum and x.
        int diff = Integer.MAX_VALUE;

        // res_l and res_r are result indexes from ar1[] and ar2[]
        // respectively
        int res_l = 0, res_r = 0;

        // Start from left side of ar1[] and right side of ar2[]
        int l = 0, r = n - 1;
        while (l < m && r >= 0) {
            // If this pair is closer to x than the previously
            // found closest, then update res_l, res_r and diff
            if (Math.abs(ar1[l] + ar2[r] - x) < diff) {
                res_l = l;
                res_r = r;
                diff = Math.abs(ar1[l] + ar2[r] - x);
            }

            // If sum of this pair is more than x, move to smaller
            // side
            if (ar1[l] + ar2[r] > x)
                r--;
            else // move to the greater side
                l++;
        }

        // Print the result
        System.out.print("The closest pair is [" + ar1[res_l] + ", " + ar2[res_r] + "]");
    }

    // Driver program to test above functions
    public static void main(String args[])
    {
        ClosestPair ob = new ClosestPair();
        int ar1[] = { 1, 4, 5, 7 };
        int ar2[] = { 10, 20, 30, 40 };
        int m = ar1.length;
        int n = ar2.length;
        int x = 38;
        ob.printClosest(ar1, ar2, m, n, x);
    }
}
/*This code is contributed by Rajat Mishra */

Output:

The closest pair is [7, 30]

Time Complexity : O(n) 
Auxiliary Space : O(1)

Please refer complete article on Find the closest pair from two sorted arrays for more details!