C++ STL <algorithm> is really a treasure trove of surprises!

Permutations

Heaps

• make_heap
• push_heap
• pop_heap
• sort_heap
• is_heap
• is_heap_until

Sorting

• sort
• stable_sort
• partial_sort
• nth_element
• sort_heap
• inplace_merge
• is_sorted
• is_sorted_until