Codesignal - depositProfit

You have deposited a specific amount of money into your bank account. Each year your balance increases at the same growth rate. With the assumption that you don't make any additional deposits, find out how long it would take for your balance to pass a specific threshold.

 

Example

For deposit = 100, rate = 20, and threshold = 170, the output should be
depositProfit(deposit, rate, threshold) = 3.

Each year the amount of money in your account increases by 20%. So throughout the years, your balance would be:

• year 0: 100;
• year 1: 120;
• year 2: 144;
• year 3: 172.8.

Thus, it will take 3 years for your balance to pass the threshold, so the answer is 3.

 

Input/Output

• [execution time limit] 20 seconds (swift)
• [input] integer depositGuaranteed constraints:
  1 ≤ deposit ≤ 100.
• The initial deposit, guaranteed to be a positive integer.
• [input] integer rateGuaranteed constraints:
  1 ≤ rate ≤ 100.
• The rate of increase. Each year the balance increases by the rate percent of the current sum.
• [input] integer thresholdGuaranteed constraints:
  deposit < threshold ≤ 200.
• The target balance.
• [output] integer
• The number of years it would take to hit the threshold.

설명

deposit이 threshold값에 근접 할 때까지 rate의 비율로 증가 시켰을 때, 몇 회 만에 근접한 숫자가 되는가

 

풀이

func depositProfit(deposit: Int, rate: Int, threshold: Int) -> Int {
    var result = Double(deposit)
    var count = 0

    while true {
        if result > Double(threshold) || result == Double(threshold) {
            return count
        } else {
            result = Double(result) + (Double(result) * (Double(rate)/100))
            count += 1
        }
    }
    return count
}