Reverse String without using Recursion

Write an iterative program to reverse a given string.


For example,

Input:  Techie Delight

Output: thgileD eihceT


Approach 1: Using build-in methods

Simple approach will be to use strrev() function in C or std::reverse in C++ or StringBuilder.reverse() method in java.


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Approach 2: Using stack

We can easily reverse a given string using stack data structure. We initially push every character of the string into the stack and then we start filling the input string (starting from index 0) by popping characters from the stack until it is empty.


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The time complexity of above solution is O(n) and auxiliary space used by the program is O(n) for stack.

Approach 3: in-place conversion

Above solution takes O(n) for stack which is not recommended. We can easily solve this problem in linear time and O(1) space. Below is the iterative in-place solution –


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Related Posts: Reverse a string using recursion

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