Divide-and-conquer algorithm

A divide-and-conquer algorithm is a recursive algorithm that recursively breaks down a problem into \(2\) or more subproblems until they can be solved directly, and then combines the solutions to the subproblems to construct a solution to the original problem.

It's possible to write an algorithm that finds the minimum element in a sequence through a divide-and-conquer approach that splits the sequence repeatedly until it becomes trivial to find the minimum, then working up by comparing the results of subproblems: 

algorithm find_minimum is
    input: a sequence L
    output: the smallest number in L

    if L has just 1 element x (base case)
        return x
    else (recursive case)
        halve L into 2 sequences A and B
        min_a ← find_minimum(A)
        min_b ← find_minimum(B)
        if min_a ≤ min_b
            return min_a
        else
            return min_b
⚠ You might be worried that if the length of L is odd, it cannot be halved. It's okay, just get as close to halving the sequence as possible.
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