求三个数最大乘积

# 求三个数最大乘积
# 思路：三个数都是正数，则取最大三个数；三个数都是复数，也取最大三个数；有正有负，取最小的2个负数、最大的正数

# 排序求解
from math import inf


def func1(li:list):
    li.sort()
    return max(li[0]*li[1]*li[-1], li[-1]*li[-2]*li[-3])

# 线性扫描求解
def func2(li:list):
    import sys
    # min1 = sys.maxsize
    # min2 = sys.maxsize
    # max1 = -sys.maxsize-1
    # max2 = -sys.maxsize-1
    # max3 = -sys.maxsize-1
    min1 = float('inf')
    min2 = float('inf')
    max1 = float('-inf')
    max2 = float('-inf')
    max3 =float('-inf')
    for i in li:
        if i<min1:
            min2 = min1
            min1 = i
        elif i<min2:
            min2 = i
        if i>max1:
            max3=max2
            max2 = max1
            max1 = i
        elif i > max2:
            max3=max2
            max2 = i
        elif i >max3:
            max3 = i
    return max(min1*min2*max1,max1*max2*max3)

li = [-1,-2,-3,-4,-5,-6,-7,8,-9]
print(func1(li))
print(func2(li))