***Encode and Decode Strings

Problem Link: https://www.lintcode.com/problem/659/

class Solution:
    """
    @param: strs: a list of strings
    @return: encodes a list of strings to a single string.
    """
    def encode(self, strs):
        # write your code here

        # Encoding of [lint,dj] becomes "4#lint2#dj"
        s=""
        for i in strs:
            s=s+str(len(i))+"#"+i
        return s
    """
    @param: str: A string
    @return: dcodes a single string to a list of strings
    """
    def decode(self, s):
        # write your code here
        i=0
        n=len(s)
        arr=[]
        while(i<n):
            length=""
            while(s[i]!="#"):
                length=length+s[i]
                i+=1
            length=int(length)
            i+=1
            arr.append(s[i:i+length])
            i=i+length
        return arr