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Growth of a Population

kouqhar answered on March 25, 2023 Popularity 9/10 Helpfulness 1/10

answer Growth of a Population

Growth of a Population

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/*
  In a small town 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 does the town need to see its population greater or 
  equal to p = 1200 inhabitants? 
  (** number of inhabitants is an integer **)

  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

  At the end of the 3rd year there will be:
  1141 + 1141 * 0.02 + 50 => 1213

  It will need 3 entire years.
  More generally given parameters:

  p0, percent, aug (inhabitants coming or leaving each year), 
  	p (population to equal or surpass)

  the function nb_year should return n number of entire years needed 
  to get a population greater or equal to p.

  aug is an integer, percent a positive or null floating number, 
  	p0 and p are positive integers (> 0)

  Examples:
  nb_year(1500, 5, 100, 5000) -> 15
  nb_year(1500000, 2.5, 10000, 2000000) -> 10
  
  Note:
  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.
*/

// ********** METHOD ONE ********
const nbYear = (p0, percent, aug, p) => {
    let years = [p0]
    let i = years.at(-1)
    
    while(i < p){
      const lastIndex = years.at(-1)
      const convertedPercent = percent / 100
      const inhabitants = Math.floor(lastIndex + lastIndex 
                                     * convertedPercent + aug)
      
      if(lastIndex >= p) 
        // Subtract 1, cause you've added the latest inhabitants number
        return years.length - 1 
      else {
        i++
        i = lastIndex
      }
      
      years.push(inhabitants)
    } 
}

// ********** METHOD TWO ********
let years = []
const nbYear = (p0, percent, aug, p) => {
  years.push(p0)
  
  let result = 0
  const convertedPercent = percent / 100
  const inhabitants = Math.floor(p0 + p0 * convertedPercent + aug)
  
  if(inhabitants < p) 
    return nbYear(inhabitants, percent, aug, p)
  else {
    result = years.length
    years = []
  } 
  return result
}

// With love @kouqhar

Popularity 9/10 Helpfulness 1/10 Language javascript

Source: www.codewars.com

Tags: javascript population

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Contributed on Mar 25 2023

kouqhar

0 Answers Avg Quality 2/10

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