151. Reverse Words in a String 186.Reverse Words in a String II 翻转单词顺序列

本文主要是介绍151. Reverse Words in a String 186.Reverse Words in a String II 翻转单词顺序列，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

题目描述

牛客最近来了一个新员工Fish，每天早晨总是会拿着一本英文杂志，写些句子在本子上。同事Cat对Fish写的内容颇感兴趣，有一天他向Fish借来翻看，但却读不懂它的意思。例如，“student. a am I”。后来才意识到，这家伙原来把句子单词的顺序翻转了，正确的句子应该是“I am a student.”。Cat对一一的翻转这些单词顺序可不在行，你能帮助他么？

解答

我们使用wi来表示第i个单词，用wi’表示翻转后的单词。注意，当将一个单词翻转两次后，可以得到原始的单词，即(wi’)’=wi。
输入的字符串是w1w2…wn。如果我们翻转整个字符串，我们将得到wn’…w2’w1’。然后我们将单词逐个翻转，就可以得到wn…w2w1。

class Solution {
public:void reverseWords(string &s) {int length = s.length();reverse(s.begin(),s.end());int read = 0;int write = 0;while(read < length){//skip leading white space and more than one white spaces between wordsif(s[read] == ' ')++read;else{//record the start of a wordint wordStart = read;//count the length of a wordwhile(read < length && s[read] != ' ')++read;//reverse  current word reverse(s.begin() + wordStart,s.begin() + read);//copy current word to the appropriate positioncopy(s.begin() + wordStart,s.begin() + read,s.begin() + write);//move write to the end of current wordwrite += read - wordStart;//add white space between wordsif(write < length)s[write] = ' ';//move write one step forward   ++write;}}//s is not a empty string or string of white spacesif (write){s = s.substr(0,write-1);}elses = "";}
};