## Expert Answer

**Solution:**

*Graph:*

Following is an undirected weighted graph. The weight of the edge between a and b is 4, the edge between a and c is 1, the edge between b and c is 2 and the edge between b and d is 1.

**Distance traversal tree:**

The tree rooted at node a is created such that :

- number of edges = number of vertices – 1(which is the characteristic of a tree) = 4 – 1 = 3.
- and the edges are chosen such that the total distance traversed from root a to d is minimum.

*To construct the tree the rules written below are to be followed:*

**Construct an adjacency matrix. An edge between a vertex v to v is marked as (infinity) to denote prevention of self loop in the tree. An edge between two vertices v and u are marked as 0 if there is no edge available between them.****Start from the root node s. Find the minimum edge e corresponding to the row of the root node. Mark the edge s->v and go to the row corresponding to v. Mark e in that row and find the minimum edge in that row ( except edge e).****Repeat the previous step until an edge makes a circuit in the tree.**

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*Adjacency matrix for the graph:*

*Distance traversal tree:*