How to calculate the average of digits of a number recursively? [closed]

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Specifically with Java, tough the solution should开发者_高级运维 basically work with other languages.

For example, 12345 would return 3.

Thanks.

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Recursive solution:

double averageDigits(int number, int sum, int count) {
    if(number==0) {
        if(count==0) {
            return 0;
        }
        return ((double) sum) / ((double) count);
    }
    else {
        return averageDigits(number/10, sum + number % 10, ++count);
    }
}

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If you have only integer numbers you might want to check mod "%" and simple division "/" and combine it with a loop to count and sum the number parts.

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in pseudo code:

split the number in a list of digeds and then calc the avg recursiv

double avg(List<Integer> list) {
  if(list.length==0) return 0;
    else return (list.get(0)+ (avg(list.sublist(1)*(lisr.length()-1)))
               /list.length();
}

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Don't know about java, in javascript, this would work

function avrg(arr){
   avrg.arr = avrg.arr || arr.slice();
   avrg.l = avrg.l || 1/arr.length;
   return arr.length ? (avrg.l*avrg.arr.pop()+avrg(avrg.arr)) : 0;
}

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public String getAverage(String num) {
    try {
        Integer.parseInt(num);
    } catch (NumberFormatException e) {
        return "Invalid number";
    }
    int length = num.length();
    int total;
    int i;
    String[] digits = num.split("");
    for (String s : digits) {
        i = Integer.parseInt(s);
        total += i;
    }
    return (total / length).toString();
}

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This does the trick:

public class DigitAverage {

    public static void main(String[] args) {
        System.out.println(digitAverage(12345));
    }

    private static double digitAverage(int remainder, int... depth) {

        boolean first = false;
        if (depth.length == 0) {
            depth = new int[] { 1 };
            first = true;
        } else {
            depth[0] = depth[0] + 1;
        }
        if (remainder < 10) {
            return remainder;
        }
        double result = remainder % 10 + digitAverage(remainder / 10, depth);
        if (first) {
            result = result / depth[0];
        }
        return result;
    }
}

Notice this function only requires the number as input, no internal 'bookkeeping' parameters of the recursion have be initialized by the caller.