Find Minimum Days to Eat N Oranges in Python

Suppose we have a number n. So consider there are n oranges in the kitchen and we eat some of these oranges every day maintaining these rules: 1. Eat single orange. 2. If n is even, then eat n/2 oranges. 3. If n is divisible by 3 can eat 2*(n/3) oranges. We can select only one option each day. We have to find the minimum number of days to eat n oranges.

So, if the input is like n = 10, then the output will be 4 because

• On day 1 eat 1 orange, 10 - 1 = 9.

• On day 2 eat 6 oranges, 9 - 2*(9/3) = 9 - 6 = 3.

• On day 3 eat 2 oranges, 3 - 2*(3/3) = 3 - 2 = 1.

• On day 4 eat the last orange 1 - 1 = 0.

To solve this, we will follow these steps −

• Define a function fun() . This will take n

• if n is in memo, then

  • return memo[n]

• if n<=2, then

  • return n

• memo[n]:= 1 + minimum of (n mod 2+ fun(quotient of n/2)) and (n mod 3 + fun(quotient of n/3))

• return memo[n]

• From the main method, do the following

• memo:= a new map

• return fun(n)

Example

Let us see the following implementation to get better understanding

def solve(n):
   def fun(n):
      if n in memo:
         return memo[n]
      if n<=2:
         return n
      memo[n]=1+min(n%2+fun(n//2),n%3+fun(n//3))
      return memo[n]
   memo={}
   return fun(n)

n = 12
print(solve(n))

Input

7, [5,1,4,3]

Output

4