Given an input string, reverse the string word by word. A word is defined as a sequence of non-space characters.
The input string does not contain leading or trailing spaces and the words are always separated by a single space.
For example,
Given s = "the sky is blue",
return "blue is sky the".
Could you do it in-place without allocating extra space?
Related problem: Rotate Array
Runtime: 6ms
1 class Solution { 2 public: 3 void reverseWords(string &s) { 4 // reverse the entire string 5 reverseString(s, 0, s.size() - 1); 6 7 // reverse each single word 8 for (int i = 0; i < s.size(); ) { 9 int wordEndNext = s.find(" ", i); 10 // reach to end 11 if (wordEndNext == s.npos) { 12 reverseString(s, i, s.size() - 1); 13 return; 14 } else { 15 reverseString(s, i, wordEndNext - 1); 16 i = wordEndNext + 1; 17 } 18 } 19 } 20 21 void reverseString(string &s, int begin, int end) { 22 for (int i = begin, j = end; i < j; i++, j--) 23 swap(s[i], s[j]); 24 } 25 };
原文：http://www.cnblogs.com/amazingzoe/p/5895643.html