C Program to find a minimum spanning tree using Prim’s algorithm


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Prims algorithm is a greedy algorithm that finds the minimum spanning tree of a graph. Graph should be weighted, connected, and undirected.

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C Program

#include<stdio.h>
#include<conio.h>
int a,b,u,v,n,i,j,ne=1;
int visited[10]= {
	0
}
,min,mincost=0,cost[10][10];
void main() {
	clrscr();
	printf("\n Enter the number of nodes:");
	scanf("%d",&n);
	printf("\n Enter the adjacency matrix:\n");
	for (i=1;i<=n;i++)
	  for (j=1;j<=n;j++) {
		scanf("%d",&cost[i][j]);
		if(cost[i][j]==0)
		    cost[i][j]=999;
	}
	visited[1]=1;
	printf("\n");
	while(ne<n) {
		for (i=1,min=999;i<=n;i++)
		   for (j=1;j<=n;j++)
		    if(cost[i][j]<min)
		     if(visited[i]!=0) {
			min=cost[i][j];
			a=u=i;
			b=v=j;
		}
		if(visited[u]==0 || visited[v]==0) {
			printf("\n Edge %d:(%d %d) cost:%d",ne++,a,b,min);
			mincost+=min;
			visited[b]=1;
		}
		cost[a][b]=cost[b][a]=999;
	}
	printf("\n Minimun cost=%d",mincost);
	getch();
}





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