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返回算法分类分析

第一题 Longest Common Prefix

Write a function to find the longest common prefix string amongst an array of strings.

解法

想法比较直接，注意这里shortest的使用方法和min的使用方法。 class Solution(object):

def longestCommonPrefix(self, strs):

    """

    :type strs: List[str]

    :rtype: str

    """

    if not strs:

        return ""

    shortest = min(strs, key=len)

    for i in range(len(shortest)):

        for s in strs:

            if not s[i] == shortest[i]:

                return shortest[:i]

    return shortest

第二题 String to Integer (atoi)

解法

注意这里一开始对各种情况的处理。 在if的条件语句中，if 和 else都要出现，详见下面的例子。

class Solution(object):

def myAtoi(self, str):

    """

    :type str: str

    :rtype: int

    """

    if len(str) == 0:

        return 0



    isNegative, i, result = False, 0, 0

    while i < len(str) and str[i] == ' ': 

        i = i + 1

    if i == len(str):

        return 0

    isNegative = str[i] == '-'

    i += 1 if str[i] == '-' or str[i] == '+' else 0

    cnt = 0

    while i < len(str) and cnt <= 10:

        t = ord(str[i]) - ord('0')

        if 0 <= t <= 9:

            result = result*10 + t

        else:

            break

        i = i + 1

        cnt = cnt + 1

    result = -1 * result if isNegative else result

    if result >= 2147483647:

        return 2147483647

    elif result <= -2147483648:

        return -2147483648

    else:

        return result