[LeetCode] 541.Reverse String II

• 题目描述
• 解题思路
• 实验代码

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题目描述

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:
1. The string consists of lower English letters only.
2. Length of the given string and k will in the range [1, 10000]

解题思路

和上次的字符串反转一样，这道题我还是用到了reverse()函数，而难点在于理解题目意思，需要做一个判断，由于2*k的不确定性，想清楚就能很容易解决。

实验代码

class Solution {public:    string reverseStr(string s, int k) {        int l = s.length();        for (int i = 0; i < l; i += 2*k)            reverse(s.begin()+i, min(s.begin()+i+k, s.end()));        return s;    }};