【LeetCode】 541. Reverse String II

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]

字符串反转，每2K个字符，反转前面K个。

class Solution {public:    string myreverse(string s,int l,int r){        while(l<r){            int t=s[l];            s[l]=s[r];            s[r]=t;            l++;r--;        }        return s;    }    string reverseStr(string s, int k) {        int len=s.size();        for(int i=0;i<len;i+=2*k){            if(i+k<=len){                s=myreverse(s,i,i+k-1);            }else{                s=myreverse(s,i,len-1);            }        }        return s;    }};