**Problem is as follows** ->↵
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A tree is a connected graph that doesn't contain any cycles.↵
↵
The distance between two vertices of a tree is the length (in edges) of the shortest path between these vertices.↵
↵
You are given a tree with n vertices and a positive number k. Find the number of distinct pairs of the vertices which have a distance of exactly k between them. Note that pairs (v, u) and (u, v) are considered to be the same pair.↵
↵
**Constraints** -> 1 ≤ n ≤ 50000, 1 ≤ k ≤ 500 , Edges 1 ≤ ai, bi ≤ n.↵
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[problem:161D]↵
↵
This is my submission -> [submission:229435063]↵
↵
I think my time complexity is O(2*n*k), which is approximately 5*10^7 operations, which should work.↵
↵
Any help would be appreciated :)↵
↵
**Edit** :- I got accepted when I use language as GNU C++14 , instead of GNU C++20 (64) , although it's still on the edge of time limit. Can anyone explain why this issue could've happened?↵
↵
A tree is a connected graph that doesn't contain any cycles.↵
↵
The distance between two vertices of a tree is the length (in edges) of the shortest path between these vertices.↵
↵
You are given a tree with n vertices and a positive number k. Find the number of distinct pairs of the vertices which have a distance of exactly k between them. Note that pairs (v, u) and (u, v) are considered to be the same pair.↵
↵
**Constraints** -> 1 ≤ n ≤ 50000, 1 ≤ k ≤ 500 , Edges 1 ≤ ai, bi ≤ n.↵
↵
[problem:161D]↵
↵
This is my submission -> [submission:229435063]↵
↵
I think my time complexity is O(2*n*k), which is approximately 5*10^7 operations, which should work.↵
↵
Any help would be appreciated :)↵
↵
**Edit** :- I got accepted when I use language as GNU C++14 , instead of GNU C++20 (64) , although it's still on the edge of time limit. Can anyone explain why this issue could've happened?↵
