Example 1: dijkstra in c++
void dijkstra(int s) {
priority_queue<pair<int, int>, vector<pair<int, int> >, greater<pair<int, int> > > pq;
for (int i=0; i<N; i++) dist[i] = INF;
dist[s] = 0;
pq.push(make_pair(0, s));
while (!pq.empty()) {
pair<int, int> front = pq.top();
pq.pop();
int w = front.first, u = front.second;
if (w > dist[u]) continue;
for (int i=0; i<adj[u].size(); i++) {
pair<int, int> v = adj[u][i];
if (dist[v.first] > dist[u] + v.second) {
dist[v.first] = dist[u] + v.second;
pq.push(make_pair(dist[v.first], v.first));
}
}
}
}
Example 2: dijkstra algorithm c++
#include<bits/stdc++.h>
using namespace std;
int main()
{
int n = 9;
int mat[9][9] = { { 100,4,100,100,100,100,100,8,100},
{ 4,100,8,100,100,100,100,11,100},
{100,8,100,7,100,4,100,100,2},
{100,100,7,100,9,14,100,100,100},
{100,100,100,9,100,100,100,100,100},
{100,100,4,14,10,100,2,100,100},
{100,100,100,100,100,2,100,1,6},
{8,11,100,100,100,100,1,100,7},
{100,100,2,100,100,100,6,7,100}};
int src = 0;
int count = 1;
int path[n];
for(int i=0;i<n;i++)
path[i] = mat[src][i];
int visited[n] = {0};
visited[src] = 1;
while(count<n)
{
int minNode;
int minVal = 100;
for(int i=0;i<n;i++)
if(visited[i] == 0 && path[i]<minVal)
{
minVal = path[i];
minNode = i;
}
visited[minNode] = 1;
for(int i=0;i<n;i++)
if(visited[i] == 0)
path[i] = min(path[i],minVal+mat[minNode][i]);
count++;
}
path[src] = 0;
for(int i=0;i<n;i++)
cout<<src<<" -> "<<path[i]<<endl;
return(0);
}
Example 3: Dijkstra's Weighted Graph Shortest Path in c++
#include <limits.h>
#include <stdio.h>
#define V 9
int minDistance(int dist[], bool sptSet[])
{
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;
}
void printSolution(int dist[])
{
printf("Vertex \t\t Distance from Source\n");
for (int i = 0; i < V; i++)
printf("%d \t\t %d\n", i, dist[i]);
}
void dijkstra(int graph[V][V], int src)
{
int dist[V];
bool sptSet[V];
for (int i = 0; i < V; i++)
dist[i] = INT_MAX, sptSet[i] = false;
dist[src] = 0;
for (int count = 0; count < V - 1; count++) {
int u = minDistance(dist, sptSet);
sptSet[u] = true;
for (int v = 0; v < V; 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];
}
printSolution(dist);
}
int main()
{
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;
}