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06 April 2018

Write the Dijkstra’s algorithm for single sources shortest path problem



Dijkstra’s algorithm for single sources shortest path:

      1.      Algorithm Shortest Paths (v, cost, dist, n)
      2.      // dis [j],  1<= j <= n, is set to the length of the shortest
      3.      // path from vertex v to vertex j in a digraph G with n
      4.      // vertices. dist [v] is set to zero. G is represented by its
      5.      // cost adjacency matrix cost [1:n, 1:n]
      6.      {
      7.      for (int i=1; i<=n; i++)
      8.      { // Initialize S
      9.      S [i] = false;
   10.   dist [i] = cost [v][i];
   11.   }
   12.   S [v] = true;
   13.   dist [v] = 0.0;        // Put v in S.
   14.   for (num = 2; num < n; num ++)
   15.   {
   16.   // determine n-1 paths from v.
   17.   choose u from among those vertices not
   18.   in S such that dist [u] is minimum;
   19.   S[u] = true; // Put u in S.
   20.   for (w = 1; w <= n; w++)
   21.    // Update distances.
   22.   if ((S[w] = false) && (dist[w] > dist[u] + cost[u][w])) then dist[w] = dist[u] + cost[u][w];
   23.   }
   24.   }

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