Minimum Spanning Tree Prim's Algorithm in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the key array with infinite values.

DSA Typescript

const key: number[] = new Array(V).fill([1]);

Drag options to blanks, or click blank then click option'

A0

B-1

CInfinity

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 instead of Infinity causes incorrect minimum edge selection.

Using null or -1 can cause runtime errors when comparing weights.

We use Infinity to represent that initially all vertices have an infinite key value before being updated.

2fill in blank

medium

Complete the code to mark the starting vertex as included in MST.

DSA Typescript

mstSet[[1]] = true;

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AV - 1

B1

C-1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Starting from vertex 1 or -1 causes index errors or skips the first vertex.

Using V - 1 starts from the last vertex, which is not standard.

The algorithm starts from vertex 0, so we mark mstSet[0] as true to include it first.

3fill in blank

hard

Fix the error in the loop condition to find the vertex with minimum key value not yet included in MST.

DSA Typescript

for (let v = 0; v < [1]; v++) {

Drag options to blanks, or click blank then click option'

Akey.length

BV

CmstSet.length

Dgraph.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using mstSet.length or key.length may work but is less clear.

Using graph.length may cause errors if graph is adjacency matrix with different dimensions.

The loop must run from 0 to V (number of vertices) to check all vertices.

4fill in blank

hard

Fill both blanks to update key and parent arrays when a better edge is found.

DSA Typescript

if (graph[u][v] && mstSet[v] === false && graph[u][v] < [1][v]) {
  [2][v] = u;
}

Drag options to blanks, or click blank then click option'

Akey

Bparent

CmstSet

Dgraph

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing key and parent arrays causes wrong MST construction.

Updating mstSet or graph instead causes logic errors.

We update key[v] with the new smaller weight and set parent[v] to u to record the MST edge.

5fill in blank

hard

Fill all three blanks to complete the key update inside the loop.

DSA Typescript

key[v] = graph[[1]][[2]];
mstSet[[3]] = true;

Drag options to blanks, or click blank then click option'

Au

Bv

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping u and v causes wrong edge weight assignment.

Marking mstSet[v] instead of mstSet[u] causes incorrect MST inclusion.

We update key[v] with the weight from u to v, and mark mstSet[u] as true to include vertex u in MST.