python - Python列表中被“n”整除的重复元素的最大索引

我有一个排序的数字列表，比如：

a = [77,98,99,100,101,102,198,199,200,200,278,299,300,300,300]

我需要找到每个值的最大索引，它可以被100整除。
输出应为：4,10,15
My Code:

a = [77,98,99,100,101,102,198,199,200,200,278,299,300,300,300]
idx = 1
for i in (a):
    if i%100 == 0:
        print idx
    idx = idx+1

以上代码输出：

4
9
10
13
14
15

最佳答案

为了防止人们好奇，我将dict理解技术与反向迭代技术进行了对比。听写理解的速度是原来的两倍。更改为OrderedDict导致大幅度减速。大约比听写慢15倍。

def test1():
    a = [77,98,99,100,101,102,198,199,200,200,278,299,300,300,300]
    max_index = {}
    for i, item in enumerate(a[::-1]):
        if item not in max_index:
            max_index[item] = len(a) - (i + 1)
    return max_index

def test2():
    a = [77,98,99,100,101,102,198,199,200,200,278,299,300,300,300]
    return {item: index for index, item in enumerate(a, 1)}

def test3():
    a = [77,98,99,100,101,102,198,199,200,200,278,299,300,300,300]
    OrderedDict((item, index) for index, item in enumerate(a, 1))

if __name__ == "__main__":
    import timeit
    print(timeit.timeit("test1()", setup="from __main__ import test1"))
    print(timeit.timeit("test2()", setup="from __main__ import test2"))
    print(timeit.timeit("test3()", setup="from __main__ import test3; from collections import OrderedDict"))

3.40622282028
1.97545695305
26.347012043

关于python - Python列表中被“n”整除的重复元素的最大索引，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/45597956/