原题 77. 翻转单词顺序

第一种 利用 stringstream ssin(s);

class Solution {
public:
    string reverseWords(string s) {
        if (s.size() <= 1) {
            return s;
        }
        stringstream ssin(s);
        string str;
        vector<string> words;
        while (ssin >> str) {
            words.push_back(str);
        }
        str = "";
        for (int i = words.size() - 1; i >= 0; i--) {
            str += words[i] + " ";
        }
        str = str.substr(0, str.size() - 1);
        return str;
    }
};

第二种 利用双指针

class Solution {
public:
    string reverseWords(string s) {
        if (s.size() <= 1) {
            return s;
        }
        vector<string> words;
        for (int i = 0, j = 0; i < s.size(); i=++j) {
            // 找到单词结尾
            while (s[j] != ' ' && j < s.size()) {
                j++;
            }
            // cout << s.substr(i, j - i) << endl;
            words.push_back(s.substr(i, j - i));
        }
        string res;
        for (int i = words.size() - 1; i >= 0; i--) {
            res += words[i] + " ";
        }
        return res.substr(0, res.size() - 1);
    }
};