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Find the number closest to n and divisible by m
• Difficulty Level : Easy
• Last Updated : 16 Apr, 2021

Given two integers n and m. The problem is to find the number closest to n and divisible by m. If there are more than one such number, then output the one having maximum absolute value. If n is completely divisible by m, then output n only. Time complexity of O(1) is required.
Constraints: m != 0
Examples:

```Input : n = 13, m = 4
Output : 12

Input : n = -15, m = 6
Output : -18
Both -12 and -18 are closest to -15, but
-18 has the maximum absolute value.```

We find value of n/m. Let this value be q. Then we find closest of two possibilities. One is q * m other is (m * (q + 1)) or (m * (q – 1)) depending on whether one of the given two numbers is negative or not.
Algorithm:

```closestNumber(n, m)
Declare q, n1, n2
q = n / m
n1 = m * q

if (n * m) > 0
n2 = m * (q + 1)
else
n2 = m * (q - 1)

if abs(n-n1) < abs(n-n2)
return n1
return n2  ```

## C++

 `// C++ implementation to find the number closest to n``// and divisible by m``#include ` `using` `namespace` `std;` `// function to find the number closest to n``// and divisible by m``int` `closestNumber(``int` `n, ``int` `m)``{``    ``// find the quotient``    ``int` `q = n / m;``    ` `    ``// 1st possible closest number``    ``int` `n1 = m * q;``    ` `    ``// 2nd possible closest number``    ``int` `n2 = (n * m) > 0 ? (m * (q + 1)) : (m * (q - 1));``    ` `    ``// if true, then n1 is the required closest number``    ``if` `(``abs``(n - n1) < ``abs``(n - n2))``        ``return` `n1;``    ` `    ``// else n2 is the required closest number   ``    ``return` `n2;   ``}` `// Driver program to test above``int` `main()``{``    ``int` `n = 13, m = 4;``    ``cout << closestNumber(n, m) << endl;``    ` `    ``n = -15; m = 6;``    ``cout << closestNumber(n, m) << endl;``    ` `    ``n = 0; m = 8;``    ``cout << closestNumber(n, m) << endl;``    ` `    ``n = 18; m = -7;``    ``cout << closestNumber(n, m) << endl;``    ` `    ``return` `0;``}`

## Java

 `// Java implementation to find the number closest to n``// and divisible by m``public` `class` `close_to_n_divisible_m {``    ` `    ``// function to find the number closest to n``    ``// and divisible by m``    ``static` `int` `closestNumber(``int` `n, ``int` `m)``    ``{``        ``// find the quotient``        ``int` `q = n / m;``         ` `        ``// 1st possible closest number``        ``int` `n1 = m * q;``         ` `        ``// 2nd possible closest number``        ``int` `n2 = (n * m) > ``0` `? (m * (q + ``1``)) : (m * (q - ``1``));``         ` `        ``// if true, then n1 is the required closest number``        ``if` `(Math.abs(n - n1) < Math.abs(n - n2))``            ``return` `n1;``         ` `        ``// else n2 is the required closest number   ``        ``return` `n2;   ``    ``}``     ` `    ``// Driver program to test above``    ``public` `static` `void` `main(String args[])``    ``{``        ``int` `n = ``13``, m = ``4``;``        ``System.out.println(closestNumber(n, m));``         ` `        ``n = -``15``; m = ``6``;``        ``System.out.println(closestNumber(n, m));``         ` `        ``n = ``0``; m = ``8``;``        ``System.out.println(closestNumber(n, m));``         ` `        ``n = ``18``; m = -``7``;``        ``System.out.println(closestNumber(n, m));``    ``}``}``// This code is contributed by Sumit Ghosh`

## Python3

 `# Python 3 implementation to find``# the number closest to n` `# Function to find the number closest``# to n and divisible by m``def` `closestNumber(n, m) :``    ``# Find the quotient``    ``q ``=` `int``(n ``/` `m)``    ` `    ``# 1st possible closest number``    ``n1 ``=` `m ``*` `q``    ` `    ``# 2nd possible closest number``    ``if``((n ``*` `m) > ``0``) :``        ``n2 ``=` `(m ``*` `(q ``+` `1``))``    ``else` `:``        ``n2 ``=` `(m ``*` `(q ``-` `1``))``    ` `    ``# if true, then n1 is the required closest number``    ``if` `(``abs``(n ``-` `n1) < ``abs``(n ``-` `n2)) :``        ``return` `n1``    ` `    ``# else n2 is the required closest number``    ``return` `n2``    ` `    ` `# Driver program to test above``n ``=` `13``; m ``=` `4``print``(closestNumber(n, m))` `n ``=` `-``15``; m ``=` `6``print``(closestNumber(n, m))` `n ``=` `0``; m ``=` `8``print``(closestNumber(n, m))` `n ``=` `18``; m ``=` `-``7``print``(closestNumber(n, m))` `# This code is contributed by Nikita tiwari.`

## C#

 `// C# implementation to find the``// number closest to n and divisible by m``using` `System;` `class` `GFG {` `    ``// function to find the number closest to n``    ``// and divisible by m``    ``static` `int` `closestNumber(``int` `n, ``int` `m)``    ``{``        ``// find the quotient``        ``int` `q = n / m;` `        ``// 1st possible closest number``        ``int` `n1 = m * q;` `        ``// 2nd possible closest number``        ``int` `n2 = (n * m) > 0 ? (m * (q + 1)) : (m * (q - 1));` `        ``// if true, then n1 is the required closest number``        ``if` `(Math.Abs(n - n1) < Math.Abs(n - n2))``            ``return` `n1;` `        ``// else n2 is the required closest number``        ``return` `n2;``    ``}` `    ``// Driver program to test above``    ``public` `static` `void` `Main()``    ``{``        ``int` `n = 13, m = 4;``        ``Console.WriteLine(closestNumber(n, m));` `        ``n = -15;``        ``m = 6;``        ``Console.WriteLine(closestNumber(n, m));` `        ``n = 0;``        ``m = 8;``        ``Console.WriteLine(closestNumber(n, m));` `        ``n = 18;``        ``m = -7;``        ``Console.WriteLine(closestNumber(n, m));``    ``}``}` `// This code is contributed by Sam007`

## PHP

 ` 0 ?``        ``(``\$m` `* (``\$q` `+ 1)) : (``\$m` `* (``\$q` `- 1));``    ` `    ``// if true, then n1 is the``    ``// required closest number``    ``if` `(``abs``(``\$n` `- ``\$n1``) < ``abs``(``\$n` `- ``\$n2``))``        ``return` `\$n1``;``    ` `    ``// else n2 is the required``    ``// closest number``    ``return` `\$n2``;``}` `// Driver Code``\$n` `= 13;``\$m` `= 4;``echo` `closestNumber(``\$n``, ``\$m``), ``"\n"``;` `\$n` `= -15;``\$m` `= 6;``echo` `closestNumber(``\$n``, ``\$m``), ``"\n"``;` `\$n` `= 0;``\$m` `= 8;``    ``echo` `closestNumber(``\$n``, ``\$m``), ``"\n"``;` `\$n` `= 18;``\$m` `= -7;``    ``echo` `closestNumber(``\$n``, ``\$m``), ``"\n"``;` `// This code is contributed by jit_t``?>`

## Javascript

 ``

Output:

```12
-18
0
21```

Time Complexity: O(1)
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