run.py

def find_turnaround(boat_speed, run_speed, distance):
    return distance * (1 + boat_speed / run_speed) / 2


def get_input(prompt, default):
    try:
        return float(input(prompt))
    except:
        return default


def convert_pace(pace, default):
    try:
        mins, secs = map(float, pace.split(':'))
        return 3600 / (60 * mins + secs)
    except:
        return default


def main():
    boat_speed = get_input('Boat speed (kph, default 5.0): ', 5.0)
    run_speed = convert_pace(input('Run pace (min/km, default 5:00): '), 12.0)
    distance = get_input('Desired distance (km, default 10.0): ', 10.0)
    turnaround = find_turnaround(boat_speed, run_speed, distance)
    print(
        'Turn around after {:.1f}km to run a total {:.1f}km at {:.1f}kph if the boat is going {:.1f}kph'
        .format(turnaround, distance, run_speed, boat_speed)
    )



if __name__ == '__main__':
    main()