Can you provide examples of greedy algorithm proofs and explain how they demonstrate the optimality of the algorithm's solutions?
Greedy algorithms are proven to be optimal through various techniques, such as the exchange argument and the matroid intersection theorem. One example is the proof of the greedy algorithm for the minimum spanning tree problem, where it is shown that the algorithm always produces a tree with the minimum weight. Another example is the proof of the greedy algorithm for the activity selection problem, which demonstrates that the algorithm always selects the maximum number of compatible activities. These proofs typically involve showing that the greedy choice at each step leads to an optimal solution overall.