【leetcode】1324. Print Words Vertically

题目如下：

Given a string s. Return all the words vertically in the same order in which they appear in s.
Words are returned as a list of strings, complete with spaces when is necessary. (Trailing spaces are not allowed).
Each word would be put on only one column and that in one column there will be only one word.

Example 1:

Input: s = "HOW ARE YOU"
Output: ["HAY","ORO","WEU"]
Explanation: Each word is printed vertically. 
 "HAY"
 "ORO"
 "WEU"

Example 2:

Input: s = "TO BE OR NOT TO BE"
Output: ["TBONTB","OEROOE","   T"]
Explanation: Trailing spaces is not allowed. 
"TBONTB"
"OEROOE"
"   T"

Example 3:

Input: s = "CONTEST IS COMING"
Output: ["CIC","OSO","N M","T I","E N","S G","T"]

Constraints:

• 1 <= s.length <= 200
• s contains only upper case English letters.
• It's guaranteed that there is only one space between 2 words.

解题思路：题目不难。我的方法是把所有的字符串存入一个二维矩阵中，矩阵的行数是s中单词的数量，列数是s中最长的单词的长度；最后再垂直方向遍历矩阵即可。

代码如下：

class Solution(object):
    def printVertically(self, s):
        """
        :type s: str
        :rtype: List[str]
        """
        words = s.split(' ')
        max_len = 0
        for w in words:
            max_len = max(max_len,len(w))

        res = []


        grid = [[''] * max_len for _ in words]

        for i in range(len(words)):
            for j in range(max_len):
                if j >= len(words[i]):
                    grid[i][j] = ' '
                    continue
                grid[i][j] = words[i][j]

        for j in range(len(grid[i])):
            val = ''
            for i in range(len(grid)):
                val += grid[i][j]
            val = val.rstrip()
            res.append(val)
        return res