Setup
Implement a function to calculate the growth of a population of people. The function should be able to take several parameters, including p0
(starting population), percent
, aug
(inhabitants coming or leaving each year), and p
(population to surpass). This function should output n(number of years needed to get a population of p
).
Don't forget to convert the percent parameter as a percentage in the body of your function: if the parameter percent is 2 you have to convert it to 0.02.
Example
In our example, the population is p0 = 1000 at the beginning of a year. The population regularly increases by 2 percent per year and moreover 50 new inhabitants per year come to live in the town.
How many years need to pass for the town to see its population greater or equal to p = 1200 inhabitants?
At the end of the first year there will be: 1000 + 1000 * 0.02 + 50 => 1070 inhabitants At the end of the 2nd year there will be: 1070 + 1070 * 0.02 + 50 => 1141 inhabitants (number of inhabitants is an integer) At the end of the 3rd year there will be: 1141 + 1141 * 0.02 + 50 => 1213 It will need 3 entire years.
Tests
nbYear(1500, 5, 100, 5000)
nbYear(1500000, 2.5, 10000, 2000000)
nbYear(1500000, 0.25, 1000, 2000000)
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Top comments (8)
Haskell
Starting population : p0
Percent : pct
Inhabitants coming or leaving each year : aug
Population to surpass : p
After n years the total population will be :
(p0 + aug/pct) * ( (1 + pct)n ) - aug/pct
where aug is converted from percentage i.e. from 5% to 0.05
So, n >= (log((aug + pct*p) / (aug + pct*p0) ) / log(1+pct))
Here is the C++ solution
Output :
Elm
I was too lazy, just put floats everywhere.
Tests
Python solution
.NET anyone?
pretty straight forward calculation, checked in a while-loop with a counter.
Got the whole thing over here github.com/AWeleczka/dev-to_daily-... with application and tests. That's also where my solutions are, don't want to spoil this thread any more ;)
Javascript
Codepen
In Python:
Python