541. Reverse String II

题目来源【Leetcode】

Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of them. If there are less than 2k but greater than or equal to k characters, then reverse the first k characters and left the other as original.
Example:
Input: s = “abcdefg”, k = 2
Output: “bacdfeg”
Restrictions:
The string consists of lower English letters only.
Length of the given string and k will in the range [1, 10000]

这道题就是考虑好最后剩下的那部分的转化就没啥问题了

class Solution {public:    string reverseStr(string& s, int k) {        int l = s.length();        if(l < k) {            reverse(&s[0],&s[l]);            return s;        }        int i = 0;        while(i < l && l-i >= k){            int end = i+k-1;            cout<<i<<" "<<end<<endl;            reverse(&s[i],&s[i+k]);            i += 2*k;        }        reverse(&s[i],&s[l]);        return s;    }};