1324. Print Words Vertically

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.

class Solution {
 public List<String> printVertically(String s) {
        String[] words = s.split(" ");
        int mx = 0;
        for (int i = 0; i < words.length; ++i)
            mx = Math.max(mx, words[i].length());
        List<String> ans = new ArrayList<>();
        for (int i = 0; i < mx; ++i) {
            StringBuilder sb = new StringBuilder();
            for (String word : words)
                sb.append(i < word.length() ? word.charAt(i) : " ");
            while (sb.charAt(sb.length() - 1) == ' ')
                sb.deleteCharAt(sb.length() - 1); // remove trailing space.
            ans.add(sb.toString());
        }
        return ans;
    }
}

脑子一团浆糊，没办法有效地利用数据结构，很伤，其实还是蛮简单的。做题要有大局观，知道每一步对接下来的影响才行。

记得remove最后面不需要的space