What is the difference between dynamic programming and greedy algorithms?

What is the difference between dynamic programming and greedy algorithms?

Dynamic programming and greedy algorithms are both optimization techniques, but they differ in approach. Dynamic programming solves problems by breaking them down into simpler subproblems and storing the results to avoid redundant calculations. Greedy algorithms, on the other hand, make the locally optimal choice at each step with the hope of finding a global optimum.

Can you give me an example of each?

Sure! A classic example of dynamic programming is the Fibonacci sequence, where each number is the sum of the two preceding ones. A greedy algorithm example is the coin change problem, where you choose the largest denomination coin first to minimize the number of coins used.

When should I use dynamic programming instead of greedy?

You should use dynamic programming when the problem has overlapping subproblems and optimal substructure, meaning that the solution can be constructed efficiently from solutions to subproblems. Greedy algorithms are suitable when local optimal choices lead to a global optimum.

Are there any problems that can be solved by both methods?

Yes, some problems can be solved using both methods, but they may yield different results. For example, the Knapsack problem can be approached with both dynamic programming and a greedy method, but only the dynamic programming approach guarantees an optimal solution.