Given an input string, reverse the string word by word.
For example, Given s = "the sky is blue", return "blue is sky the".
Update (2015-02-12): For C programmers: Try to solve it in-place in O(1) space.
Clarification: What constitutes a word? 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 about multiple spaces between two words? Reduce them to a single space in the reversed string. 解法简述： 逐个取元素，第一个循环排除空格，第二个循环在遇到空格或null前将字幕出入缓存单元的第一个位置，这样在遇到空格时为一个正序的单词； 再设定一个缓存string 每获得一个单词就拼接起来末尾加空格； 最后拼接完后，因为排除空格的循环设在第一位，导致最后若存在多个空格时会存入多个空格，因此多设一层循环排除末尾多出空格。 代码如下： class Solution { public: void reverseWords(string &s) { string rs,temp; int i = s.length()-1; while(s[i] != NULL){ while(s[i] == ' ' && s[i] != NULL) i--; while(s[i] != ' ' && s[i] != NULL){ temp.insert(0,1,s[i]); i--; } rs = rs + temp + " "; temp = ""; i--; } rs = rs + temp; s = rs; i = s.length()-1; while(s[i] == ' '){ s.erase(i ,1); i--; } } };