Parallel algorithm for finding the maximum in $\log n$ time using $n / \log n$ processors
Divide your original array into $n/\log n$ blocks of length $\log n$. Put each processor in charge of each block, and find the maximum using the usual algorithm in time $\log n$. We now need to compute the maximum of an array of length $n/\log n$. Pair up the elements and compute the pairwise maxima to reduce the size of the array by a half. Repeat it $\log n$ times to find the maximum of the entire array.

The same idea also shows that you can compute the maximum in parallel in constant time using $n^{1+\epsilon}$ computers for every $\epsilon &gt; 0$. (Exercise.)