Notes on this puzzle
13 clues around the edge, out of a possible 28, frame this 7×7 grid. 7 heights are already standing inside the grid.
The bottom edge carries the most clues (4). 15 edge positions are blank, so parts of the grid are solved from the inside out.
Where to beginTry row 4, column 1 first: its row and column clues decide it without any other help. Use notes for the heights 6 and 7 first; once they are placed, the lower heights follow.