541. 反转字符串 II 2021-08-20

class Solution {
public:
    string reverseStr(string s, int k) {
        auto it = s.begin();
        while (it + 2 * k < s.end()) {
            reverse(it, it + k);
            it += 2 * k;
        }
        if (s.end() - it >= k)
            reverse(it, it + k);
        else
            reverse(it, s.end());
        return s;
    }
};