A few quick observations:
- If moving upwards consume $$$10^{100}$$$ stamina for each step, then answer for starting vertex $$$v_i$$$ is obviously the deepest children of the subtree rooted at $$$v_i$$$.
- If $$$k_i = 1$$$, denote $$$p$$$ as direct parent of $$$v_i$$$ (we assume that $$$v_i \ne 1$$$ i.e., there exists a node $$$p$$$), then the answer is the maximal distance from $$$v_i$$$ between the deepest children of the subtree rooted at $$$v_i$$$ and the deepest children of the subtree rooted at $$$p$$$ minus subtree rooted at $$$v_i$$$.
We can treat the second part as a reroot: if initially root is $$$p$$$ and then it's handed down to $$$v_i$$$, the distance of all nodes in subtree $$$v_i$$$ drop by $$$1$$$, but the distance of all nodes in subtree $$$p$$$ minus subtree $$$v_i$$$ increase by $$$1$$$. This can be rephrase as: increase all distance by $$$1$$$, drop subtree $$$v_i$$$ by $$$2$$$.
Thus, we can solve the queries offline.
For each query $$$(v_i, k_i)$$$, the scanning scope (i.e., reachable nodes) will be the subtree rooted at the ancestor exactly $$$k_i$$$ steps away from $$$v_i$$$ (or $$$1$$$ if such ancestor doesn't exist).
Here, we assume that you have already calculated all the depth of nodes in the case of root being $$$1$$$. Then, perform a DFS. When reaching each node $$$x$$$, add $$$1$$$ to all depths and subtract $$$2$$$ to the depths under subtree $$$x$$$. Then, solve every query $$$(x, k_i)$$$ simply by finding the maximal depth among nodes under subtree $$$p$$$, with $$$p$$$ being the ancestor exactly $$$k_i$$$ steps away from $$$x$$$ (or $$$1$$$).
Maintaining depths like this can be done with a post-Euler-tour segment tree.