LeetCode 1 Reverse Words in a String

题目 Reverse Words in a String

Given an input string, reverse the string word by word.

For example,

Given s = "the sky is blue",

return "blue is sky the".

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 st

思路：首先将原始字符串按照word切分成单词数组，然后将单词数组逆序使用空格连接起来。
class Solution {
public:
vector<string> split(const string &s, char c) {
vector<string> v;

int start = -1;
bool flag = false;
for(int i = 0; i < s.length(); i ++){
if(flag == false) {
if(s[i] != c) {
start = i;
flag = true;
}
}
else {
if(s[i] == c){
flag = false;
v.push_back(s.substr(start, i - start));
}
}
}
if(flag){
v.push_back(s.substr(start, s.length() - start));
}
return v;
}
void reverseWords(string &s) {
vector<string> substrings = split(s, ' ');
s.erase();
if(substrings.size() > 0) {
for(vector<string>::reverse_iterator rit = substrings.rbegin(); rit != substrings.rend(); rit ++) {
s += *rit;
s.push_back(' ');
}
s.pop_back();
}
}
};