Reverse String II Problem
Description
LeetCode Problem 541.
Given a string s and an integer k, reverse the first k characters for every 2k characters counting from the start of the string.
If there are fewer 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 1:
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Input: s = "abcdefg", k = 2
Output: "bacdfeg"
Example 2:
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Input: s = "abcd", k = 2
Output: "bacd"
Constraints:
- 1 <= s.length <= 10^4
- s consists of only lowercase English letters.
- 1 <= k <= 10^4
Sample C++ Code
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class Solution {
public:
string reverseStr(string s, int k) {
for (int left = 0; left < s.size(); left += 2 * k) {
for (int i = left, j = min(left + k - 1, (int)s.size() - 1); i < j; i++, j--) {
swap(s[i], s[j]);
}
}
return s;
}
};