Top and Bottom view

Assign root horizontal distance zero, left child distance minus one, and right child plus one. Run BFS with pairs of node and distance. For top view, record a distance only the first time BFS reaches it: level order guarantees that first node is shallowest, with left-to-right queue order resolving ties consistently. For bottom view, overwrite the value whenever a node at that distance is visited, so later and deeper nodes survive; clarify the prompt's tie rule if equal-depth collisions matter. Finally output distances from minimum to maximum, or use an ordered map. Each node is visited once, giving O(n) time plus O(w log w) if sorting w columns, and O(n) queue/map space. Check a skewed tree, a single node, and overlapping columns.