#字符串 #颠倒字符串中的单词

reverse-words-in-a-string.cpp

class Solution {
public:
    string reverseWords(string s) {
        reverse(s.begin(), s.end());
        int str_len = 0;
        int l = -1;
        for (int i = 0; i < s.size(); ++i) {
            if (l >= 0 && s[i] == ' ') {
                reverse(s.begin() + l,  s.begin() + i);
                for (int k = 0; k < i - l; ++k) {
                    s[str_len++] = s[l+k];
                }
                if (i < s.size())
                    s[str_len++] = ' ';
                l = -1;
            } else if (s[i] != ' ' && l < 0) {
                l = i;
            }
        }

        // last word
        if (l >= 0) {
            reverse(s.begin() + l,  s.end());
            for (int k = 0; k < s.size() - l; ++k) {
                s[str_len++] = s[l+k];
            }
        }

        // remove space in the end of sentence
        while (str_len > 0 && s[str_len - 1] == ' ')
            str_len--;
        s.resize(str_len);
        return s;
    }
};