In level-order traversal, the last node processed per level is the rightmost visible node.
BFS by levels. For each level, append the value of the last node popped.
BFS groups nodes by depth; within a depth, the rightmost node is the one seen from the right side.
In level-order traversal, the last node processed per level is the rightmost visible node.
BFS by levels. For each level, append the value of the last node popped.
BFS groups nodes by depth; within a depth, the rightmost node is the one seen from the right side.