easy solution
Intuition\nThe task is to reverse the first k characters of every 2k characters in a given string s. This can be done by iterating through the string in chunks 
# Intuition\nThe task is to reverse the first `k` characters of every `2k` characters in a given string `s`. This can be done by iterating through the string in chunks of `2k` and reversing the first `k` characters within each chunk.\n\n# Approach\n1. Iterate through the string with a step of `2k`:\n   - For each `2k` segment, identify the first `k` characters.\n   - Reverse these `k` characters.\n   - Move to the next `2k` segment and repeat the process.\n2. If the remaining characters are fewer than `k`, reverse all of them.\n3. If the remaining characters are between `k` and `2k`, reverse the first `k` characters and leave the rest as they are.\n\n# Complexity\n- **Time complexity:** $$O(n)$$\n  - We are iterating through the string with a step size of `2k`, and within each step, we reverse `k` characters. Thus, the time complexity is linear with respect to the length of the string.\n- **Space complexity:** $$O(1)$$\n  - We are modifying the string in place and using a constant amount of extra space for temporary variables.\n\n# Code\n```\nclass Solution {\npublic:\n    string reverseStr(string s, int k) {\n        for (int i=0; i<s.length(); i=i+k+k){\n            int j=i, m=j+k-1 ;\n            while (j <= m){\n                if (m>s.length()-1) m = s.length()-1 ;\n                swap(s[j++], s[m--]) ;\n            }\n        }\n        return s ;\n    }\n};\n```
['Two Pointers', 'String', 'C++']