一道关于字符串压缩的面试题

题目

编写一个算法，实现基本的字符串“压缩”算法，比如对于字符串'abbbbffcccdddcc'，经过算法处理之后得到的输出为'a1b4f2c3d3c2'，如果处理后的字符串长度不小于原串长度，则返回原串。

算法

算法一

def str_compress(string):
    result = []
    current = string[0]
    count = 1
    for s in string[1:]:
        if s == current:
            count += 1
        else:
#             result += current + str(count)
            result.append(current)
            result.append(str(count))
            current = s
            count = 1
#     result += current + str(count)
    result.append(current)
    result.append(str(count))
#     return result
    return ''.join(result)

s = 'abbbbffcccdddcc'
print(str_compress(s))

a1b4f2c3d3c2

算法二

# 使用itertools模块的groupby方法
from itertools import groupby

def str_compress2(string):
    result = []
    for key, group in groupby(string):
        result.append(key)
        result.append(str(len(list(group))))
    return ''.join(result)

s = 'abbbbffcccdddcc'
print(str_compress2(s))

a1b4f2c3d3c2

更多groupby及itertools模块的用法请参考：

http://www.liaoxuefeng.com/wiki/001374738125095c955c1e6d8bb493182103fac9270762a000/001415616001996f6b32d80b6454caca3d33c965a07611f000

• http://www.wklken.me/posts/2013/08/20/python-extra-itertools.html#itertoolsgroupbyiterable-key