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Competition Arena > ExactTreeEasy
SRM 662 · 2015-06-30 · by cgy4ever · Math
Class Name: ExactTreeEasy
Return Type: int[]
Method Name: getTree
Arg Types: (int, int)
Problem Statement

Problem Statement

You are given ints n and m. Construct any tree with exactly n nodes (labeled 0 through n-1) and exactly m leaves. For the given constraints on n and m a solution will always exist.

The return value should be a int[] containing a sequence of 2*(n-1) integers. If your tree has edges (a[0], b[0]), (a[1], b[1]), etc., the correct return value is the sequence {a[0], b[0], a[1], b[1], ...}. If there are multiple correct return values, you may return any of them.

Notes

  • A tree is a connected acyclic graph. The leaf of a tree is a node of degree 1, i.e., a node that has exactly one outgoing edge.

Constraints

  • n will be between 3 and 50, inclusive.
  • m will be between 2 and n-1, inclusive.
Examples
0)
4
2
Returns: {0, 1, 1, 2, 2, 3 }

We are supposed to construct a tree with 4 nodes and 2 leaves. One such tree is a simple path consisting of the edges 0-1, 1-2, and 2-3.

1)
4
3
Returns: {0, 1, 1, 2, 1, 3 }

Now we have to construct a tree with 4 nodes and 3 leaves. The tree returned by our solution contains the edges 1-0, 1-2, and 1-3. The leaves are the nodes 0, 2, and 3.

2)
3
2
Returns: {0, 1, 1, 2 }
3)
5
3
Returns: {0, 1, 1, 2, 1, 3, 3, 4 }
4)
10
9
Returns: {0, 1, 1, 2, 1, 3, 1, 4, 1, 5, 1, 6, 1, 7, 1, 8, 1, 9 }

Submissions are judged against all 24 archived test cases, of which 5 are shown here. Case numbers match the judge’s.

Coding Area

Language: C++17 · define a public class ExactTreeEasy with a public method vector<int> getTree(int n, int m) · 24 test cases · 2 s / 256 MB per case

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