C# 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

C#

// C# program to find closest pair in
// an array
using System;

class GFG {

    // 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.
    static void printClosest(int[] ar1,
                             int[] ar2, int m, int n, int x)
    {

        // Initialize the diff between pair
        // sum and x.
        int diff = int.MaxValue;

        // 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
        Console.Write("The closest pair is ["
                      + ar1[res_l] + ", "
                      + ar2[res_r] + "]");
    }

    // Driver program to test above functions
    public static void Main()
    {
        int[] ar1 = { 1, 4, 5, 7 };
        int[] ar2 = { 10, 20, 30, 40 };
        int m = ar1.Length;
        int n = ar2.Length;
        int x = 38;

        printClosest(ar1, ar2, m, n, x);
    }
}

// This code is contributed by nitin mittal.

Output:

The closest pair is [7, 30]

Time Complexity: O(m + n), where m and n represents the size of the given two arrays.
Auxiliary Space: O(1), no extra space is required, so it is a constant.

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