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prims_mst.cpp
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prims_mst.cpp
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// Ayush Bhardwaj
// Date : 07-03-23
#include <iostream>
#include <queue>
#include <utility>
#define MAX_NODES 100
using namespace std;
const int INF = 1e9;
int primMST(int graph[][MAX_NODES], int numNodes, int start) {
int dist[MAX_NODES];
bool visited[MAX_NODES] = {false};
priority_queue<pair<int,int>, vector<pair<int,int>>, greater<pair<int,int>>> pq;
// Initialize distances to all nodes as infinity
for (int i = 0; i < numNodes; i++) {
dist[i] = INF;
}
// Add the starting node to the priority queue with distance 0
pq.push(make_pair(0, start));
dist[start] = 0;
while (!pq.empty()) {
// Get the node with the minimum distance from the priority queue
int node = pq.top().second;
pq.pop();
// If the node has already been visited, skip it
if (visited[node]) {
continue;
}
visited[node] = true;
// Update distances to the neighbors of the current node
for (int neighbor = 0; neighbor < numNodes; neighbor++) {
if (graph[node][neighbor] > 0 && !visited[neighbor] && graph[node][neighbor] < dist[neighbor]) {
dist[neighbor] = graph[node][neighbor];
pq.push(make_pair(dist[neighbor], neighbor));
}
}
}
// Calculate the sum of all distances to get the total weight of the MST
int totalWeight = 0;
for (int i = 0; i < numNodes; i++) {
if (dist[i] != INF) {
totalWeight += dist[i];
}
}
return totalWeight;
}
int main() {
int graph[MAX_NODES][MAX_NODES] = {
{0, 2, 0, 6, 0},
{2, 0, 3, 8, 5},
{0, 3, 0, 0, 7},
{6, 8, 0, 0, 9},
{0, 5, 7, 9, 0}
};
int numNodes = 5;
int start = 0;
int totalWeight = primMST(graph, numNodes, start);
cout << "Total weight of the MST: " << totalWeight << endl;
return 0;
}