LeetCode:Reverse String II

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"

思路：题目比较简单，主要就是理解清楚剩余字符串的处理就可以了。

void sw(string& s, int b, int e)
{
    char t;
    while (b<e)
    {
        t = s[b];
        s[b] = s[e];
        s[e] = t;
        ++b; --e;
    } 
}
string reverseStr(string s, int k) 
{
    int len = s.length();
    int n = len / (2*k);
    int i =0;
    for (; i < n; i++)
        sw(s, i * 2 * k, i * 2 * k + k - 1);

    if (len - i * 2 * k < k)
        sw(s, i * 2 * k, len - 1);
    else
        sw(s, i * 2 * k, i * 2 * k + k-1);
        
    return s;
}

 

 

如果你有任何疑问或新的想法，欢迎在下方评论。