判断列表中的元素是否全等于某个数

有三种思路：

1. 将列表构造为集合，再判断长度
2. 用一个元素与所有元素比较
3. 比较列表第一个元素的个数和列表长度

import numpy as np
import time
import random

a = [1 for i in range(100000000)]
a[99999998] = 2

tic = time.time()
print(len(set(a)) == 1)
toc = time.time()
print(toc-tic)

False
1.0153181552886963

tic = time.time()
print(all(x == 1 for x in a))
toc = time.time()
print(toc-tic)

False
5.827450275421143

tic = time.time()
print(a.count(a[0]) == len(a))
toc = time.time()
print(toc-tic)

False
0.10375499725341797