Leetcode 541. Reverse String II

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原题链接：https://leetcode.com/problems/reverse-string-ii/description/

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

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Solution：

本题理解比较简单，就是每2k个元素翻转前k个，采用的是比较笨直接数的方法通过的，并没有很耐心的去找规律，代码如下：

#include <iostream>
#include <string>
using namespace std;

string reverseStr(string s, int k) {
    int len = s.size();
    string str = s, res = "";
    while (len > 2 * k) {
        string temp = str.substr(0, 2 * k);
        reverse(temp.begin(), temp.begin() + k);
        res += temp;
        str = str.substr(2 * k);
        len = len - 2 * k;
    }
    if (len < k) {
        reverse(str.begin(), str.end());
        res += str;
    }
    else {
        reverse(str.begin(), str.begin() + k);
        res += str;
    }
    return res;
}

int main()
{
    string s;
    int k;
    cin >> s >> k;
    cout << reverseStr(s, k) << endl;
    system("pause");
    return 0;
}