541. Reverse String II

• Difficulty: Easy

• Topics: String

• Similar Questions:

  • Reverse String

  • Reverse Words in a String III

Problem:

</p> 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. </p>

Example:

Input: s = "abcdefg", k = 2
Output: "bacdfeg"

Restrictions: </b>

Solutions:

class Solution {
public:
    string reverseStr(string s, int k) {
        int pos = 0;
        while (pos < s.length()) {
            int left = pos;
            int right = min(pos + k - 1, (int) s.length() - 1);
            while (left < right) {
                swap(s[left], s[right]);
                ++left;
                --right;
            }
            pos += 2 * k;
        }

        return s;
    }
};