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Reverse String

Certification: Basic Level Accuracy: 0% Submissions: 0 Points: 5

Write a C program to reverse a string. The input string is given as an array of characters. You must do this by modifying the input array in-place with O(1) extra memory. Do not allocate extra space for another array.

You must modify the input array in-place and perform the reversal operation with constant extra memory.

Example 1
    
  
  • Input: s = ["h","e","l","l","o"]
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  • Output: ["o","l","l","e","h"]
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  • Explanation: We start with ["h","e","l","l","o"], swap first and last characters: ["o","e","l","l","h"], swap second and second-to-last characters: ["o","l","l","e","h"]. Third character remains in place.
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Example 2
    
  
  • Input: s = ["H","a","n","n","a","h"]
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  • Output: ["h","a","n","n","a","H"]
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  • Explanation: We start with ["H","a","n","n","a","h"], then swap characters from the outside in: first and last, second and second-to-last, third and third-to-last.
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Constraints
    
  
  • 1 ≤ s.length ≤ 10^5
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  • s[i] is a printable ASCII character
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  • You must modify the array in-place with O(1) extra memory
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  • Time Complexity: O(n) where n is the length of the string
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  • Space Complexity: O(1)
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Hint
Solution

Solution Hints

    
  
  • Use a two-pointer approach to solve this problem
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  • Initialize one pointer at the beginning of the array and another at the end
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  • Swap the characters at both pointers
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  • Move the left pointer one step right and the right pointer one step left
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  • Continue until the pointers meet or cross each other
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Steps to solve by this approach:

 Step 1: Initialize two pointers - left at the beginning (index 0) and right at the end (index sSize-1) of the array.

 Step 2: While the left pointer is less than the right pointer, perform the following steps.

 Step 3: Swap the characters at positions pointed by left and right pointers using a temporary variable.

 Step 4: Increment the left pointer by 1 (move it one step to the right).

 Step 5: Decrement the right pointer by 1 (move it one step to the left).

 Step 6: Continue this process until the pointers meet or cross each other.

 Step 7: The array is now reversed in-place using O(1) extra memory.

Submitted Code :