1.(字符串)-计算n个数count-and-say

如： 

1, 11, 21, 1211, 111221, ...

1 is read off as "one 1" or 11.

11 is read off as "two 1s" or 21.

21 is read off as "one 2, then one 1" or 1211.

python：

def countAndSay(n):
    if n == 0:
        return ''
    res = '1'
    while n != 0:
        n -= 1
        print(res)
        i = 0
        count = 1
        cur = ''
        # 拼接res的读数
        while i < len(res):
            count = 1
            while i + 1 < len(res) and res[i] == res[i + 1]:
                count += 1
                i += 1
            #     数量+本身
            cur += str(count) + res[i]
            # 到下一个数字位
            i += 1
        res = cur
    return res


s = countAndSay(5)

#output

1
11
21
1211
111221