Sword finger offer notes: t58 - I. flip word order

T58 - I. Flip word order

Enter an English sentence , Turn over the order of the words in the sentence , But the order of the characters in the word is the same . For the sake of simplicity , Punctuation is treated like ordinary letters . For example, input string "I am a student. “, The output "student. a am I”.

Example 1：

Input : “the sky is blue”
Output : “blue is sky the”
Example 2：

Input : "  hello world!  "
Output : “world! hello”
explain : The input string can contain extra spaces before or after , But the reversed characters cannot include .
Example 3：

Input : “a good   example”
Output : “example good a”
explain : If there are extra spaces between two words , Reduce the space between inverted words to just one .

explain ：

No space characters make up a word .
The input string can contain extra spaces before or after , But the reversed characters cannot include .
If there are extra spaces between two words , Reduce the space between inverted words to just one .

Ideas

Double pointer , It's just the opposite

solution 1

I didn't think of it

solution 2

class Solution {
    public String reverseWords(String s) {
        String tmp = s.trim();
        int start = tmp.length() - 1;
        int end = tmp.length() - 1;
        String res = "";
        while(start >= 0) {
            while(start >= 0 && tmp.charAt(start) != ' ') {
                start--;
            }
            res += tmp.substring(start + 1, end + 1) + " ";
            while(start >= 0 && tmp.charAt(start) == ' ') {
                start--;
            }
            end = start;
        }
        return res.trim();
    }
}

Execution time ：14 ms, In all  Java  Defeated in submission **9.02%** Users of

Memory consumption ：38.9 MB, In all  Java  Defeated in submission **10.76%** Users of

author ： Painter Dapeng
link ：https://leetcode-cn.com/leetbook/read/illustrate-lcof/59otf1/
source ： Power button （LeetCode）
The copyright belongs to the author . Commercial reprint please contact the author for authorization , Non-commercial reprint please indicate the source .