#include <stdio.h>
#include <math.h>
#include <stdbool.h>

int calcE12Base(int n)
{
    int value = -1;

    if(n >= 1 && n <= 12)
    {
        value = round(10 * pow(10, (n-1)/12.0));
    }

    return value;
}

int realE12Base(int n)
{
    int value;

    switch(n)
    {
    case 1:
        value = 10;
        break;
    case 2:
        value = 12;
        break;
    case 3:
        value = 15;
        break;
    case 4:
        value = 18;
        break;
    case 5:
        value = 22;
        break;
    case 6:
        value = 27;
        break;
    case 7:
        value = 33;
        break;
    case 8:
        value = 39;
        break;
    case 9:
        value = 47;
        break;
    case 10:
        value = 56;
        break;
    case 11:
        value = 68;
        break;
    case 12:
        value = 82;
        break;
    default:
        value = -1;
    }

    return value;
}

double E12Value(int n, int p, bool calculate)
{
    double value = -1.0;

    if(calculate)
    {
        value = calcE12Base(n);
    }
    else
    {
        value = realE12Base(n);
    }

    if(value > 0 && p >= -3 && p <= 9)
    {
        value *= pow(10, p);
    }

    return value;
}

void printResistorValue(double value)
{
    double exponent = log10(value);
    int base1000exponent = (int) floor(exponent/3);
    char metricPrefix;
    value /= pow(10, base1000exponent * 3);

    switch (base1000exponent)
    {
        case -1 :
            metricPrefix = 'm';
            break;
        case 0 :
            metricPrefix = ' ';
            break;
        case 1 :
            metricPrefix = 'k';
            break;
        case 2 :
            metricPrefix = 'M';
            break;
        case 3 :
            metricPrefix = 'G';
            break;
    }
    if(value < 10)
    {
        printf("%3.1f%c", value, metricPrefix);
    }
    else
    {
        printf("%3.0f%c", value, metricPrefix);
    }
}

void printE12(bool calculate)
{
    for(int p = -3; p <= 9; p++)
    {
        for(int n = 1; n <= 12; n++)
        {
            printResistorValue(E12Value(n, p, calculate));
            printf(" ");
        }
        printf("\n");
    }
}

int main()
{
    printE12(true);

    printf("\n");

    printE12(false);

    return 0;
}