双指针算法

(双指针) $O(n)$

C++ 代码

class Solution {
public:
    string reverseWords(string s) {
        string ans;
        for(int i = 0; i < s.size(); i ++)
        {
            if(s[i] == ' ') continue;
            int j = i;
            while(j < s.size() && s[j] != ' ') j ++;
            if(ans.size()) ans = " " + ans;
            ans = s.substr(i, j - i) + ans;
            i = j;
        }
        return ans;
    }
};