Problem Description
Write a function that reverses a string. The input string is given as an array of characters s. You must do this by modifying the input array in-place with O(1) extra memory.
Key Insights
- The problem requires reversing a string represented as an array of characters.
- An in-place algorithm is necessary, meaning we cannot use additional data structures that grow with input size.
- The two-pointer technique is ideal for this problem, allowing us to swap elements efficiently.
Space and Time Complexity
Time Complexity: O(n), where n is the length of the string. Space Complexity: O(1), as we are not using any extra space that grows with input size.
Solution
We can use the two-pointer technique to reverse the string in place. We initialize one pointer at the beginning of the array and another at the end. We then swap the characters at these pointers and move the pointers towards each other until they meet. This approach ensures that we only traverse the array once, achieving the required time complexity.