# 鸡兔同笼问题
# 将鸡和兔子关在同一个笼子里，已知头有xx个，脚有xx只，求有几只兔子和几只鸡


def caculate_num(head: int, foot: int):
    rabbit = (foot - head * 2) // 2
    chicken = head - rabbit
    temp_leg_num = rabbit * 4 + chicken * 2
    if temp_leg_num == foot and rabbit >= 0 and chicken >= 0:
        return True, rabbit, chicken
    else:
        return False, 0, 0


while True:
    while True:
        head_ins = input('请输入头的数量：')
        if head_ins.isdigit():
            head_num = int(head_ins)
            break
        else:
            print('请检查输入数据，重新输入')
    while True:
        foot_ins = input('请输入脚的数量：')
        if foot_ins.isdigit():
            foot_num = int(foot_ins)
            break
        else:
            print('请检查输入数据，重新输入')

    status, rabbit, chicken = caculate_num(head_num, foot_num)
    if status:
        print('{}个头，{}只腿，计算得出鸡有{}只，兔子有{}只'.format(head_num, foot_num, chicken, rabbit))
    else:
        print('经过检查{}个头，{}只腿的数量，不符合四腿兔子两腿鸡的设定，请重新输入'.format(head_num, foot_num))

输出结果

请输入脚的数量：250
100个头，250只腿，计算得出鸡有75只，兔子有25只