Example

• Assign 1 to A (going down)
• Assign 0 to B (bottom out)
• Assign -1 to C (going up)
• These steps are O(1) given initial tree
• The depth of the node is stored in C
• A + B + C = 0
• The net effect of the subtree is 0
• Serial:
• Run ListPrefix: lg 3n = O(lg n)
• $\otimes$ here is addition
• Work: W =