<?php

// PHP program to implement Dijkstra's algorithm.

// Also known as single-source shortest path algorithm.

// It is a Greedy algorithm.

// function to find unvisited vertex with minimum distance

function getMinVertex($dist, $visited, $n){

$minVertex = -1;

for($i = 0; $i < $n; ++$i){

if(!$visited[$i] && (($minVertex == -1) || ($dist[$minVertex] > $dist[$i])) ){

$minVertex = $i;

}

}

return $minVertex;

}

function dijkstra($graph, $vertices){

$visited = array();

$dist = array();

for($i = 0; $i < $vertices; ++$i){

$visited[$i] = false;

$dist[$i] = PHP_INT_MAX;

}

// 0 is the source/starting vertex

$dist[0] = 0;

for($i = 0; $i < $vertices-1; ++$i){

$minVertex = getMinVertex($dist, $visited, $vertices);

// Mark the minVertex as visited

$visited[$minVertex] = true;

// Explore all unvisited neighbours of minVertex

// and update the dist array if required

for($j = 0; $j < $vertices; ++$j){

if($graph[$minVertex][$j] != 0 && !$visited[$j]){

$currD = $dist[$minVertex] + $graph[$minVertex][$j];

if($dist[$j] > $currD){

$dist[$j] = $currD;

}

}

}

}

// Print the vertices and their corresponding distances from the source vertex

echo "Vertex\tDistance from source\n";

for($k = 0; $k < $vertices; ++$k){

echo $k."\t".$dist[$k]."\n";

}

}

// Sample Graph (Sample Input) - Adjacency Matrix representation

$graph = array(

array(0, 3, 0, 5),

array(3, 0, 1, 0),

array(0, 1, 0, 8),

array(5, 0, 8, 0)

);

// Function for Dijkstra'a algorithm

dijkstra($graph, 4);

/*

Sample Input:

$graph = array(

array(0, 3, 0, 5),

array(3, 0, 1, 0),

array(0, 1, 0, 8),

array(5, 0, 8, 0)

);

Sample Output:

Vertex Distance from source

0 0

1 3

2 4

3 5

*/

?>