python---流程控制

1.解一元二次方程：

a, b, c = eval(input("enter a, b, c:"))
delt = b ** 2 - 4*a*c
if delt > 0:
    x1 = (-b + delt ** 0.5) / (2*a)
    x2 = (-b - delt ** 0.5) / (2*a)
    print("the roots are %.2f and %.2f" % (x1, x2))
elif delt == 0:
    x = (-b) / (2*a)
    print("the root is %.2f" % (x))
else :
    print("the equation has no real roots")

2.解线性方程：

a, b, c, d, e, f = eval(input("enter a, b, c, d, e, f:"))
delt = a*d - b*c
if delt == 0:
    print("the equation has no solution")
else:
    x = (e*d - b*f) / delt
    y = (a*f - e*c) / delt
    print("x is %.2f and y is %.2f" %(x,y))

3.彩票程序：

#程序随机产生一个两位数 ab 
#用户输入一个两位数  xy
#将两个数字的个位和十位分别拆开
#判断得奖情况
#如果 a == x and b == y 一等奖
#如果 a == y and b == x 二等奖
#如果 a == x or b == x or a == y or b == y 三等奖
#(23   13.12.21,31三等   32二等   23二等  14不得奖)
import random
num1 = random.randint(10,99)
num2= eval (input("enter a number:"))
a = num1 // 10
b = num1 % 10
x = num2 // 10
y = num2 % 10
print("中奖号码为:", num1)
if a == x and b == y:
    print("一等奖")
elif a == y and b == x:
    print("二等奖")
elif a == x or b == x or a == y or b == y:
    print("三等奖")
else:
    print("谢谢惠顾")

4.找出一个月中的天数：