Given an input string s
, reverse the order of the words.
A word is defined as a sequence of non-space characters. The words in s
will be separated by at least one space.
Return a string of the words in reverse order concatenated by a single space.
Note that s
may contain leading or trailing spaces or multiple spaces between two words. The returned string should only have a single space separating the words. Do not include any extra spaces.
Example 1:
Input: s = "the sky is blue"
Output: "blue is sky the"
Example 2:
Input: s = " hello world "
Output: "world hello"
Explanation: Your reversed string should not contain leading or trailing spaces.
Example 3:
Input: s = "a good example"
Output: "example good a"
Explanation: You need to reduce multiple spaces between two words to a single space in the reversed string.
Constraints:
-
1 <= s.length <= 104
-
s
contains English letters (upper-case and lower-case), digits, and spaces' '
. - There is at least one word in
s
.
Follow-up: If the string data type is mutable in your language, can you solve it in-place with O(1)
extra space?
SOLUTION:
class Solution:
def reverseWords(self, s: str) -> str:
n = len(s)
words = []
i = 0
for j in range(n):
if s[j] != " ":
if j == 0 or s[j - 1] == " ":
i = j
if j == n - 1 or s[j + 1] == " ":
words.append(s[i:j+1])
return " ".join(words[::-1])
Top comments (0)