Dijkstra's shortest path algorithm-2

 // A C++ program for Dijkstra's single source shortest path algorithm.

// The program is for adjacency matrix representation of the graph

#include <iostream>

using namespace std;

#include <limits.h>


// Number of vertices in the graph

#define V 9


// A utility function to find the vertex with minimum distance value, from

// the set of vertices not yet included in shortest path tree

int minDistance(int dist[], bool sptSet[])

{


// Initialize min value

int min = INT_MAX, min_index;


for (int v = 0; v < V; v++)

if (sptSet[v] == false && dist[v] <= min)

min = dist[v], min_index = v;


return min_index;

}


// A utility function to print the constructed distance array

void printSolution(int dist[])

{

cout <<"Vertex \t Distance from Source" << endl;

for (int i = 0; i < V; i++)

cout << i << " \t\t"<<dist[i]<< endl;

}


// Function that implements Dijkstra's single source shortest path algorithm

// for a graph represented using adjacency matrix representation

void dijkstra(int graph[V][V], int src)

{

int dist[V]; // The output array. dist[i] will hold the shortest

// distance from src to i


bool sptSet[V]; // sptSet[i] will be true if vertex i is included in shortest

// path tree or shortest distance from src to i is finalized


// Initialize all distances as INFINITE and stpSet[] as false

for (int i = 0; i < V; i++)

dist[i] = INT_MAX, sptSet[i] = false;


// Distance of source vertex from itself is always 0

dist[src] = 0;


// Find shortest path for all vertices

for (int count = 0; count < V - 1; count++) {

// Pick the minimum distance vertex from the set of vertices not

// yet processed. u is always equal to src in the first iteration.

int u = minDistance(dist, sptSet);


// Mark the picked vertex as processed

sptSet[u] = true;


// Update dist value of the adjacent vertices of the picked vertex.

for (int v = 0; v < V; v++)


// Update dist[v] only if is not in sptSet, there is an edge from

// u to v, and total weight of path from src to v through u is

// smaller than current value of dist[v]

if (!sptSet[v] && graph[u][v] && dist[u] != INT_MAX

&& dist[u] + graph[u][v] < dist[v])

dist[v] = dist[u] + graph[u][v];

}


// print the constructed distance array

printSolution(dist);

}


// driver program to test above function

int main()

{


/* Let us create the example graph discussed above */

int graph[V][V] = { { 0, 4, 0, 0, 0, 0, 0, 8, 0 },

{ 4, 0, 8, 0, 0, 0, 0, 11, 0 },

{ 0, 8, 0, 7, 0, 4, 0, 0, 2 },

{ 0, 0, 7, 0, 9, 14, 0, 0, 0 },

{ 0, 0, 0, 9, 0, 10, 0, 0, 0 },

{ 0, 0, 4, 14, 10, 0, 2, 0, 0 },

{ 0, 0, 0, 0, 0, 2, 0, 1, 6 },

{ 8, 11, 0, 0, 0, 0, 1, 0, 7 },

{ 0, 0, 2, 0, 0, 0, 6, 7, 0 } };


dijkstra(graph, 0);


return 0;

}


// This code is contributed by shivanisinghss2110


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