Given an integer N > 0, the task is to find the maximum product of digits among numbers less than or equal to N.
Input: N = 390
Maximum possible product is given by the number 389
3 * 8 * 9 = 216
Input: N = 432
Approach: This problem can also be solved using the method described in this article taking lower limit as 1 and upper limit as N. Another method to solve this problem is by using recursion. The conditions for recursion are as follows:
- If N = 0 then return 1.
- If N < 10 then return N.
- Otherwise, return max(maxProd(N / 10) * (N % 10), maxProd((N / 10) – 1) * 9
At each step of recursion, either the last digit or 9 is taken to maximize the product of digit.
Below is the implementation of the above approach:
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