Calculate Years to Reach Target Amount in Python

Suppose we have some parameters P,O,E,T. If we have P dollars in principal that we want to invest the stock market. The stock market alternates between first returning E and then O percent interest per year, we have to check how many years it would take to reach at least T dollars.

So, if the input is like P = 200, O = 10, E = 25, T = 300, then the output will be 3 as in the first year we will get interest 25%, so end up with 200+50 = 250, then next year we will get 10%, so end up with 250+25 = 275, then again get 10% in the next year, so it will be 275+27.5 = 302.5, this is greater than 300, so 3 years required.

To solve this, we will follow these steps −

• ans:= 0
• while P < T, do
  • P := P * 1+(E/100)
  • ans := ans + 1
  • if P < T, then
    • P := P * 1+(O/100)
    • ans := ans + 1
• return ans

Let us see the following implementation to get better understanding −

Example

class Solution:
   def solve(self, P, O, E, T):
      ans=0
      while P < T:
         P *= 1+(E/100)
         ans += 1
         if P < T:
            P *= 1+(O/100)
            ans += 1
      return ans
ob = Solution()
P = 200
O = 10
E = 25
T = 300
print(ob.solve(P,O,E,T))

Input

P = 200, O = 10, E = 25, T = 300

Output

3