Do you personally prefer tree problem with $$$N-1$$$ pair of integers input where $$$i^{th}$$$ input ($$$u_i$$$ and $$$v_i$$$) denotes the nodes that $$$i^{th}$$$ edge connects (and all the edges guarantee a tree) or $$$N-1$$$ integers input where $$$i^{th}$$$ input ($$$p_i$$$) indicates that there is an edge that connects node $$$i+1$$$ and node $$$p_i$$$ (usually this comes with the $$$1 \leq p_i \leq i$$$ constraint)? I personally prefer the latter.