Add missing `#include <algorithm>` (#61)
Add missing `#include <algorithm>` (#61)

An upcoming compiler release updates libc++ to stop exporting `<algorithm>`
from certain headers [1]. This means code using functions from `<algorithm>`
but relying on them existing from transitive header dependencies will now be
broken.

[1] The commit: https://github.com/llvm/llvm-project/commit/2e2f3158c604adb8401a2a44a03f58d4b6f1c7f9
dsharlet/array