Explain the concept of memoization and how it can be used for code optimisation.

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Explain the concept of memoization and how it can be used for code optimisation.

Memoization is a technique used in computer programming to optimize the execution time of a function by caching its results. It involves storing the results of expensive function calls and returning the cached result when the same inputs occur again. This can significantly improve the performance of the code, especially when dealing with recursive or repetitive computations.

The concept of memoization revolves around the idea of trading off space complexity for time complexity. By storing the results of function calls, we avoid redundant computations and reduce the overall time taken to execute the code.

To implement memoization, we typically use a data structure like a dictionary or an array to store the computed results. The input parameters of the function are used as keys, and the corresponding output is stored as the value. Before executing the function, we check if the result is already present in the cache. If it is, we return the cached result instead of recomputing it. If not, we compute the result and store it in the cache for future use.

Memoization is particularly useful in scenarios where a function is called multiple times with the same inputs. For example, in recursive algorithms like Fibonacci or factorial, the same subproblems are often computed repeatedly. By memoizing the results, we can avoid redundant computations and drastically reduce the time complexity of the algorithm.

The benefits of using memoization for code optimization include:

1. Improved performance: Memoization reduces the time complexity of a function by avoiding redundant computations. This can lead to significant performance improvements, especially for functions with expensive calculations or recursive calls.

2. Reduced complexity: By caching the results, the code becomes simpler and easier to understand. It eliminates the need for repetitive calculations and allows developers to focus on the core logic of the function.

3. Scalability: Memoization allows for efficient handling of large inputs or complex computations. It ensures that the function does not waste time recomputing results that have already been calculated.

However, it is important to note that memoization is not suitable for all scenarios. It is most effective when the function has a high probability of being called with the same inputs multiple times. Additionally, care must be taken to handle cases where the function's output can change over time or when the cache size becomes too large, leading to excessive memory usage.

In conclusion, memoization is a powerful technique for code optimization that can significantly improve the performance of functions by caching their results. It reduces redundant computations and allows for faster execution, making it a valuable tool in optimizing time-critical code.