题目描述：

LeetCode 467. Unique Substrings in Wraparound String

Consider the string s to be the infinite wraparound string of "abcdefghijklmnopqrstuvwxyz", so s will look like this: "...zabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcd....".

Now we have another string p. Your job is to find ...

题目描述：

LeetCode 469. Convex Polygon

Given a list of points that form a polygon when joined sequentially, find if this polygon is convex (Convex polygon definition).

Note:

1. There are at least 3 and at most 10,000 points.
2. Coordinates are ...

题目描述：

LeetCode 434. Number of Segments in a String

Count the number of segments in a string, where a segment is defined to be a contiguous sequence of non-space characters.

For example,

Input: "Hello, my name is John"

Output: 5 ...

利用Python计算1000以内自然数的约数个数，然后通过matplotlib绘制统计图。

绘制图片为约数个数的散点图及其分布情况的条形图。

Python代码：

import collections
import matplotlib.pyplot as plt

def countDivisors(num):
    ans = 1
    x = 2
    while x * x <= num:
        cnt = 1
        while num % x == 0:
            cnt += 1
            num /= x
        ans *= cnt
        x += 1
    return ans * (1 ...

方法I 从1到n枚举，判断是否可以整除

时间复杂度 O(n)

Python代码：

def countDivisors(num):
    return sum(num % i == 0 for i in range(1, num + 1))

方法II 从1到sqrt(n)枚举，判断是否可以整除

时间复杂度 O( sqrt(n) )

Python代码：

def countDivisors(num):
    cnt = 0
    sqrt = int(num ...