Integers X and K are given. The task is to find the highest K-digit number divisible by X.
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.
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