Integers X and K are given. The task is to find the highest K-digit number divisible by X.
Examples:
Input : X = 30, K = 3 Output : 990 990 is the largest three digit number divisible by 30. Input : X = 7, K = 2 Output : 98
A simple solution is to try all numbers starting from the largest K digit number (which is 999…K-times) and return the first number divisible by X.
An efficient solution is to use below formula.
ans = MAX - (MAX % X) where MAX is the largest K digit number which is 999...K-times
The formula works on simple school method division. We remove remainder to get the largest divisible number.
C++
// CPP code to find highest K-digit number divisible by X #include <bits/stdc++.h> using namespace std; // Function to compute the result int answer( int X, int K) { // Computing MAX int MAX = pow (10, K) - 1; // returning ans return (MAX - (MAX % X)); } // Driver int main() { // Number whose divisible is to be found int X = 30; // Max K-digit divisible is to be found int K = 3; cout << answer(X, K); } |
Java
// Java code to find highest // K-digit number divisible by X import java.io.*; import java.lang.*; class GFG { public static double answer( double X, double K) { double i = 10 ; // Computing MAX double MAX = Math.pow(i, K) - 1 ; // returning ans return (MAX - (MAX % X)); } public static void main(String[] args) { // Number whose divisible is to be found double X = 30 ; // Max K-digit divisible is to be found double K = 3 ; System.out.println(( int )answer(X, K)); } } // Code contributed by Mohit Gupta_OMG <(0_o)> |
Python3
# Python code to find highest # K-digit number divisible by X def answer(X, K): # Computing MAX MAX = pow ( 10 , K) - 1 # returning ans return ( MAX - ( MAX % X)) X = 30 ; K = 3 ; print (answer(X, K)); # Code contributed by Mohit Gupta_OMG <(0_o)> |
C#
// C# code to find highest // K-digit number divisible by X using System; class GFG { public static double answer( double X, double K) { double i = 10; // Computing MAX double MAX = Math.Pow(i, K) - 1; // returning ans return (MAX - (MAX % X)); } public static void Main() { // Number whose divisible is to be found double X = 30; // Max K-digit divisible is to be found double K = 3; Console.WriteLine(( int )answer(X, K)); } } // This code is contributed by vt_m. |
PHP
<?php // PHP code to find highest K-digit // number divisible by X // Function to compute the result function answer( $X , $K ) { // Computing MAX $MAX = pow(10, $K ) - 1; // returning ans return ( $MAX - ( $MAX % $X )); } // Driver // Number whose divisible // is to be found $X = 30; // Max K-digit divisible // is to be found $K = 3; echo answer( $X , $K ); // This code is contributed by ajit ?> |
Output:
990
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