Math Problem Statement

Use Dijkstra's algorithm to find the shortest path between u and v based on the given graph.

Solution

To solve the given problem using Dijkstra's algorithm and find the shortest path between nodes uu and vv:


Steps of Dijkstra's Algorithm:

  1. Initialize:

    • Set the distance from uu to itself as 0.
    • Set the distance from uu to all other vertices as infinity (\infty).
    • Use a priority queue (or similar structure) to track the next closest vertex to visit.
  2. Relaxation:

    • Pick the vertex with the smallest tentative distance (starting with uu).
    • Update the distances to its neighbors if a shorter path is found.
    • Repeat for all unvisited vertices.
  3. Termination:

    • Stop when the target vertex vv has been processed.

Applying the Algorithm:

Step-by-Step Solution:

Graph Representation:

  • Vertices: u,v,w,x,y,zu, v, w, x, y, z (as per the diagram).
  • Edge weights as shown.
  1. Initialization:

    • Distances: d[u]=0d[u] = 0, d[v]=d[v] = \infty, d[w]=d[w] = \infty, d[x]=d[x] = \infty, d[y]=d[y] = \infty, d[z]=d[z] = \infty.
    • Unvisited: {u,v,w,x,y,z}\{ u, v, w, x, y, z \}.
  2. Iteration:

    From uu:

    • Visit uu: d[u]=0d[u] = 0.
    • Update neighbors:
      • w:d[w]=min(,0+6)=6w: d[w] = \min(\infty, 0 + 6) = 6,
      • x:d[x]=min(,0+5)=5x: d[x] = \min(\infty, 0 + 5) = 5.
    • Unvisited: {v,w,x,y,z}\{ v, w, x, y, z \}.

    Next Closest:

    • Visit xx: d[x]=5d[x] = 5.
    • Update neighbors:
      • w:d[w]=min(6,5+4)=6w: d[w] = \min(6, 5 + 4) = 6 (no update),
      • y:d[y]=min(,5+1)=6y: d[y] = \min(\infty, 5 + 1) = 6.
    • Unvisited: {v,w,y,z}\{ v, w, y, z \}.

    Next Closest:

    • Visit ww: d[w]=6d[w] = 6.
    • Update neighbors:
      • z:d[z]=min(,6+10)=16z: d[z] = \min(\infty, 6 + 10) = 16,
      • y:d[y]=min(6,6+3)=6y: d[y] = \min(6, 6 + 3) = 6 (no update).
    • Unvisited: {v,y,z}\{ v, y, z \}.

    Next Closest:

    • Visit yy: d[y]=6d[y] = 6.
    • Update neighbors:
      • v:d[v]=min(,6+7)=13v: d[v] = \min(\infty, 6 + 7) = 13,
      • z:d[z]=min(16,6+5)=11z: d[z] = \min(16, 6 + 5) = 11.
    • Unvisited: {v,z}\{ v, z \}.

    Next Closest:

    • Visit zz: d[z]=11d[z] = 11.
    • Update neighbors:
      • v:d[v]=min(13,11+2)=13v: d[v] = \min(13, 11 + 2) = 13.
    • Unvisited: {v}\{ v \}.

    Final Visit:

    • Visit vv: d[v]=13d[v] = 13.
  3. Shortest Path: The shortest path distance from uu to vv is 13.


Backtracking the Path:

  1. Start at vv (distance = 13).
  2. From zz to vv: cost 22 (path includes zz).
  3. From yy to zz: cost 55 (path includes yy).
  4. From xx to yy: cost 11 (path includes xx).
  5. From uu to xx: cost 55.

Path: uxyzvu \to x \to y \to z \to v.


Would you like a detailed explanation of any step, or do you need a graphical illustration of this process?


Related Questions:

  1. How is Dijkstra's algorithm different from Bellman-Ford?
  2. Can this graph be solved with a different algorithm like A*?
  3. How would you modify this process if negative weights existed?
  4. How does the priority queue improve the efficiency of Dijkstra's algorithm?
  5. How would the algorithm change if the goal was to find all-pairs shortest paths?

Tip:

When solving with Dijkstra's algorithm, always double-check updates to ensure you account for the lowest-cost path for each step!

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Math Problem Analysis

Mathematical Concepts

Graph Theory
Shortest Path Algorithms

Formulas

d[v] = min(d[v], d[u] + weight(u, v))

Theorems

Dijkstra's Algorithm

Suitable Grade Level

Undergraduate (or Advanced High School Level)