思路

和《反转字符串》的代码类似，只是每次处理2k个

代码

class Solution {
public:
    string reverseStr(string s, int k) {
        int length = s.length();
        int reverse = 0;
        while(reverse < length){
            int left, right;
            if(reverse + k <= length){
                left = reverse, right = reverse + k - 1;
            }else{
                left = reverse, right = length - 1;
            }
            while(left < right){
                swap(s[left], s[right]);
                left++;
                right--;
            }
            reverse += 2*k;
        }
        return s;
    }
};