Find closest number in array - GeeksforGeeks

10 Sep, 2021
Given an array of sorted integers. We need to find the closest value to the given number. Array may contain duplicate values and negative numbers. 
Examples:  
Input : arr[] = {1, 2, 4, 5, 6, 6, 8, 9}
             Target number = 11
Output : 9
9 is closest to 11 in given array

Input :arr[] = {2, 5, 6, 7, 8, 8, 9}; 
       Target number = 4
Output : 5
A simple solution is to traverse through the given array and keep track of absolute difference of current element with every element. Finally return the element that has minimum absolution difference.
An efficient solution is to use Binary Search.  
C++
Java
Python3
C#
PHP
Javascript
// CPP program to find element// closest to given target.#include <bits/stdc++.h>using namespace std; int getClosest(int, int, int); // Returns element closest to target in arr[]int findClosest(int arr[], int n, int target){    // Corner cases    if (target <= arr[0])        return arr[0];    if (target >= arr[n - 1])        return arr[n - 1];     // Doing binary search    int i = 0, j = n, mid = 0;    while (i < j) {        mid = (i + j) / 2;         if (arr[mid] == target)            return arr[mid];         /* If target is less than array element,            then search in left */        if (target < arr[mid]) {             // If target is greater than previous            // to mid, return closest of two            if (mid > 0 && target > arr[mid - 1])                return getClosest(arr[mid - 1],                                  arr[mid], target);             /* Repeat for left half */            j = mid;        }         // If target is greater than mid        else {            if (mid < n - 1 && target < arr[mid + 1])                return getClosest(arr[mid],                                  arr[mid + 1], target);            // update i            i = mid + 1;        }    }     // Only single element left after search    return arr[mid];} // Method to compare which one is the more close.// We find the closest by taking the difference// between the target and both values. It assumes// that val2 is greater than val1 and target lies// between these two.int getClosest(int val1, int val2,               int target){    if (target - val1 >= val2 - target)        return val2;    else        return val1;} // Driver codeint main(){    int arr[] = { 1, 2, 4, 5, 6, 6, 8, 9 };    int n = sizeof(arr) / sizeof(arr[0]);    int target = 11;    cout << (findClosest(arr, n, target));} // This code is contributed bu Smitha Dinesh Semwal
// Java program to find element closest to given target.import java.util.*;import java.lang.*;import java.io.*; class FindClosestNumber {         // Returns element closest to target in arr[]    public static int findClosest(int arr[], int target)    {        int n = arr.length;         // Corner cases        if (target <= arr[0])            return arr[0];        if (target >= arr[n - 1])            return arr[n - 1];         // Doing binary search        int i = 0, j = n, mid = 0;        while (i < j) {            mid = (i + j) / 2;             if (arr[mid] == target)                return arr[mid];             /* If target is less than array element,               then search in left */            if (target < arr[mid]) {                        // If target is greater than previous                // to mid, return closest of two                if (mid > 0 && target > arr[mid - 1])                    return getClosest(arr[mid - 1],                                  arr[mid], target);                                 /* Repeat for left half */                j = mid;                         }             // If target is greater than mid            else {                if (mid < n-1 && target < arr[mid + 1])                    return getClosest(arr[mid],                          arr[mid + 1], target);                               i = mid + 1; // update i            }        }         // Only single element left after search        return arr[mid];    }     // Method to compare which one is the more close    // We find the closest by taking the difference    //  between the target and both values. It assumes    // that val2 is greater than val1 and target lies    // between these two.    public static int getClosest(int val1, int val2,                                         int target)    {        if (target - val1 >= val2 - target)            return val2;               else            return val1;           }     // Driver code    public static void main(String[] args)    {        int arr[] = { 1, 2, 4, 5, 6, 6, 8, 9 };        int target = 11;        System.out.println(findClosest(arr, target));    }}
# Python3 program to find element# closest to given target. # Returns element closest to target in arr[]def findClosest(arr, n, target):     # Corner cases    if (target <= arr[0]):        return arr[0]    if (target >= arr[n - 1]):        return arr[n - 1]     # Doing binary search    i = 0; j = n; mid = 0    while (i < j):        mid = (i + j) // 2         if (arr[mid] == target):            return arr[mid]         # If target is less than array        # element, then search in left        if (target < arr[mid]) :             # If target is greater than previous            # to mid, return closest of two            if (mid > 0 and target > arr[mid - 1]):                return getClosest(arr[mid - 1], arr[mid], target)             # Repeat for left half            j = mid                 # If target is greater than mid        else :            if (mid < n - 1 and target < arr[mid + 1]):                return getClosest(arr[mid], arr[mid + 1], target)                             # update i            i = mid + 1             # Only single element left after search    return arr[mid]  # Method to compare which one is the more close.# We find the closest by taking the difference# between the target and both values. It assumes# that val2 is greater than val1 and target lies# between these two.def getClosest(val1, val2, target):     if (target - val1 >= val2 - target):        return val2    else:        return val1 # Driver codearr = [1, 2, 4, 5, 6, 6, 8, 9]n = len(arr)target = 11print(findClosest(arr, n, target)) # This code is contributed by Smitha Dinesh Semwal
// C# program to find element// closest to given target.using System; class GFG{         // Returns element closest    // to target in arr[]    public static int findClosest(int []arr,                                  int target)    {        int n = arr.Length;         // Corner cases        if (target <= arr[0])            return arr[0];        if (target >= arr[n - 1])            return arr[n - 1];         // Doing binary search        int i = 0, j = n, mid = 0;        while (i < j)        {            mid = (i + j) / 2;             if (arr[mid] == target)                return arr[mid];             /* If target is less            than array element,            then search in left */            if (target < arr[mid])            {                         // If target is greater                // than previous to mid,                // return closest of two                if (mid > 0 && target > arr[mid - 1])                    return getClosest(arr[mid - 1],                                 arr[mid], target);                                 /* Repeat for left half */                j = mid;                        }             // If target is            // greater than mid            else            {                if (mid < n-1 && target < arr[mid + 1])                    return getClosest(arr[mid],                         arr[mid + 1], target);                        i = mid + 1; // update i            }        }         // Only single element        // left after search        return arr[mid];    }     // Method to compare which one    // is the more close We find the    // closest by taking the difference    // between the target and both    // values. It assumes that val2 is    // greater than val1 and target    // lies between these two.    public static int getClosest(int val1, int val2,                                 int target)    {        if (target - val1 >= val2 - target)            return val2;            else            return val1;        }     // Driver code    public static void Main()    {        int []arr = {1, 2, 4, 5,                     6, 6, 8, 9};        int target = 11;        Console.WriteLine(findClosest(arr, target));    }} // This code is contributed by anuj_67.
<?php// PHP program to find element closest// to given target. // Returns element closest to target in arr[]function findClosest($arr, $n, $target){    // Corner cases    if ($target <= $arr[0])        return $arr[0];    if ($target >= $arr[$n - 1])        return $arr[$n - 1];     // Doing binary search    $i = 0;    $j = $n;    $mid = 0;    while ($i < $j)    {        $mid = ($i + $j) / 2;         if ($arr[$mid] == $target)            return $arr[$mid];         /* If target is less than array element,            then search in left */        if ($target < $arr[$mid])        {             // If target is greater than previous            // to mid, return closest of two            if ($mid > 0 && $target > $arr[$mid - 1])                return getClosest($arr[$mid - 1],                                  $arr[$mid], $target);             /* Repeat for left half */            $j = $mid;        }         // If target is greater than mid        else        {            if ($mid < $n - 1 &&                $target < $arr[$mid + 1])                return getClosest($arr[$mid],                                  $arr[$mid + 1], $target);            // update i            $i = $mid + 1;        }    }     // Only single element left after search    return $arr[$mid];} // Method to compare which one is the more close.// We find the closest by taking the difference// between the target and both values. It assumes// that val2 is greater than val1 and target lies// between these two.function getClosest($val1, $val2, $target){    if ($target - $val1 >= $val2 - $target)        return $val2;    else        return $val1;} // Driver code$arr = array( 1, 2, 4, 5, 6, 6, 8, 9 );$n = sizeof($arr);$target = 11;echo (findClosest($arr, $n, $target)); // This code is contributed bu Sachin.?>
<script> // JavaScript program to find element// closest to given target. // Returns element closest to target in arr[]function findClosest(arr, target){    let n = arr.length;     // Corner cases    if (target <= arr[0])        return arr[0];    if (target >= arr[n - 1])        return arr[n - 1];     // Doing binary search    let i = 0, j = n, mid = 0;    while (i < j)    {        mid = (i + j) / 2;         if (arr[mid] == target)            return arr[mid];         // If target is less than array        // element,then search in left        if (target < arr[mid])        {                  // If target is greater than previous            // to mid, return closest of two            if (mid > 0 && target > arr[mid - 1])                return getClosest(arr[mid - 1],                                  arr[mid], target);                           // Repeat for left half            j = mid;                     }         // If target is greater than mid        else        {            if (mid < n - 1 && target < arr[mid + 1])                return getClosest(arr[mid],                                  arr[mid + 1],                                  target);                           i = mid + 1; // update i        }    }     // Only single element left after search    return arr[mid];} // Method to compare which one is the more close// We find the closest by taking the difference//  between the target and both values. It assumes// that val2 is greater than val1 and target lies// between these two.function getClosest(val1, val2, target){    if (target - val1 >= val2 - target)        return val2;           else        return val1;       } // Driver Codelet arr = [ 1, 2, 4, 5, 6, 6, 8, 9 ];let target = 11; document.write(findClosest(arr, target)); // This code is contributed by code_hunt </script>
Output: 
9
 
harishkumar88
vt_m
Sach_Code
code_hunt
mahee96
arorakashish0911
Binary Search
Arrays
Divide and Conquer
Searching
Arrays
Searching
Divide and Conquer
Binary Search
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