Dijkstra’s Shortest Path Algorithm

#include<bits/stdc++.h>

#define pii pair<int, int>

#define INF 1<<30

#define N 1000000

using namespace std;

vector<pii>adj[N];

int node, edge;

void dijstkra(int start)

{

priority_queue<pii, vector<pii>, greater<pii>> q;

vector<int>d(N, INF);

d[start] = 0;

q.push(pii(0, start));

while(!q.empty())

{

int u = q.top().second;

q.pop();

for(auto x : adj[u])

{

int v = x.first;

int weight = x.second;

if(d[v] > d[u] + weight)

{

d[v] = d[u] + weight;

q.push(pii(d[v], v));

}

}

}

cout << "\nDistance of Node From Source :: \n";

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

cout << start << " to " << i << " :: " << d[i] << "\n";

}

int main()

{

cout << "Enter Node Number :: ";

cin >> node; ///Here Node Count From Zero

cout << "Enter Edge Number :: ";

cin >> edge;

int n1, n2, weight, source;

cout << "\nEnter Nodes And Between Distance :: \n";

for(int i=1;i<=edge;i++)

{

cin >> n1 >> n2 >> weight;

adj[n1].push_back(pii(n2, weight));

adj[n2].push_back(pii(n1, weight));

}

cout << "\nEnter Source Node :: ";

cin >> source;

dijstkra(source);

return 0;

}