https://leetcode.com/problems/reverse-string/

Solution:

• Time complexity: O(n)

• Space complexity: O(1)

Two-pointer technique

Code:

class Solution {
    func reverseString(_ s: inout [Character]) {
        if s.count == 0 {
            return
        }
        var left = 0
        var right = s.count - 1
        while left < right {
            s.swapAt(left, right)
            left += 1
            right -= 1
        }
    }
}

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