Editing Tree traversal (section)

====Another variant of pre-order====
If the tree is represented by an array (first index is 0), it is possible to calculate the index of the next element:<ref>{{Cite web|title=constexpr tree structures|url=https://fekir.info/post/constexpr-tree/#_dfs_traversal|access-date=2021-08-15|website=Fekir's Blog|date=9 August 2021|language=en}}</ref>{{clarify|reason=Explicitly mention the restrictions on trees in order to be handled by this algorithm. Since there is no isLeaf() test, it seems that all leaves must be on maximal depth or one level above it, like in a [[heap (data structure)]].|date=November 2021}}

 '''procedure''' bubbleUp(array, i, leaf)
     k ← 1
     i ← (i - 1)/2
     '''while''' (leaf + 1) % (k * 2) ≠ k
         i ← (i - 1)/2
         k ← 2 * k
     '''return''' i
 
 '''procedure''' preorder(array)
     i ← 0
     '''while''' i ≠ array.size
         visit(array[i])
         '''if''' i = size - 1
             i ← size
         '''else if''' i < size/2
             i ← i * 2 + 1
         '''else'''
             leaf ← i - size/2
             parent ← bubble_up(array, i, leaf)
             i ← parent * 2 + 2