From d59dd12d6275c101f673fb65de39de3dcce593bc Mon Sep 17 00:00:00 2001
From: SMARTA SANGUI <40299522+SMARTA01@users.noreply.github.com>
Date: Sat, 31 Oct 2020 09:43:53 +0530
Subject: [PATCH]  Dijkstra's Algorithm

Implementation of  Dijkstra's Algorithm in C.
---
 Dijkstra's Algorithm | 75 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 Dijkstra's Algorithm

diff --git a/Dijkstra's Algorithm b/Dijkstra's Algorithm
new file mode 100644
index 00000000..0b5f9613
--- /dev/null
+++ b/Dijkstra's Algorithm	
@@ -0,0 +1,75 @@
+#include<stdio.h>
+#define INFINITY 9999
+#define MAX 10
+
+void dijikstra(int G[MAX][MAX], int n, int startnode);
+
+void main()
+{
+	int G[MAX][MAX], i, j, n, u;
+
+	printf("\nEnter the no. of vertices:: ");
+	scanf("%d", &n);
+	printf("\nEnter the adjacency matrix::\n");
+	for(i=0;i < n;i++)
+		for(j=0;j < n;j++)
+			scanf("%d", &G[i][j]);
+	printf("\nEnter the starting node:: ");
+	scanf("%d", &u);
+	dijikstra(G,n,u);
+
+}
+
+void dijikstra(int G[MAX][MAX], int n, int startnode)
+{
+	int cost[MAX][MAX], distance[MAX], pred[MAX];
+	int visited[MAX], count, mindistance, nextnode, i,j;
+	for(i=0;i < n;i++)
+		for(j=0;j < n;j++)
+			if(G[i][j]==0)
+				cost[i][j]=INFINITY;
+			else
+				cost[i][j]=G[i][j];
+
+	for(i=0;i< n;i++)
+	{
+		distance[i]=cost[startnode][i];
+		pred[i]=startnode;
+		visited[i]=0;
+	}
+	distance[startnode]=0;
+	visited[startnode]=1;
+	count=1;
+	while(count < n-1){
+		mindistance=INFINITY;
+		for(i=0;i < n;i++)
+			if(distance[i] < mindistance&&!visited[i])
+			{
+				mindistance=distance[i];
+				nextnode=i;
+			}
+		visited[nextnode]=1;
+		for(i=0;i < n;i++)
+			if(!visited[i])
+				if(mindistance+cost[nextnode][i] < distance[i])
+				{
+					distance[i]=mindistance+cost[nextnode][i];
+					pred[i]=nextnode;
+				}
+			count++;
+	}
+
+	for(i=0;i < n;i++)
+		if(i!=startnode)
+		{
+			printf("\nDistance of %d = %d", i, distance[i]);
+			printf("\nPath = %d", i);
+			j=i;
+			do
+			{
+				j=pred[j];
+				printf(" <-%d", j);
+			}
+			while(j!=startnode);
+		}
+}