CSES 1674 Subordinates - Walkthrough

Tree: $1 o 2, 3$; $2 o 4, 5$; $3 o 6$. DFS visits: $4$ (leaf, size $1$), $5$ (leaf, size $1$), then $2$ (size $1 + 1 + 1 = 3$). Then $6$ (leaf, size $1$), then $3$ (size $1 + 1 = 2$). Finally $1$ (size $1 + 3 + 2 = 6$).

Subordinates: node $1$ has $5$, node $2$ has $2$, node $3$ has $1$, nodes $4, 5, 6$ have $0$. The post-order ensures children are done before parents. This ordering is what makes tree DP work.