A sequence of non-space characters constitutes a word. Could the input string contain leading or trailing spaces? Yes. However, your reversed string should not contain leading or trailing spaces. How ...

给一个String, 里面的Word被single space split开来, 目的是reverse里面所有的Word, 但preserve Word 和 space order. Note: In the string, each word is separated by single space and there will not be any extra space in the ...