Merge pull request #432 from ushmita4/master

#376 Implementation of Dijkstra's Algorithm using C language.

Author: smv1999

Data Structures/Graphs/Dijkstra.c

@@ -0,0 +1,90 @@
+#include<stdio.h>
+#define size 50
+//Time Complexity :- O((nv)^2)
+//Space Complexity :- O(nv)
+struct vertex{
+    int dist,par,processed;
+}V[size];
+int nv;
+//relax method is used to assign the shortest value to the node.
+void relax(int w[size][size],int u,int v){
+    if(V[v].dist > V[u].dist + w[u][v]){
+        V[v].dist = V[u].dist + w[u][v];
+        V[v].par = u;
+    }
+}
+//setting the source value to zero
+void initializeSingleSource(int src){
+    int i;
+    for(i = 0; i < nv; i++){
+       V[i].dist = 99999;
+       V[i].par = -1;
+       V[i].processed = 0;
+    }
+    V[src].dist = 0;
+}
+
+void dijkstra(int w[size][size],int src){
+    int i,j,k,ver,dmin;
+    initializeSingleSource(src);
+    for(i = 0; i < nv; i++){
+        dmin = 999999;
+        for(k = 0; k < nv; k++){
+            if(!V[k].processed && V[k].dist < dmin){
+                dmin = V[k].dist;
+                ver = k;
+            }
+           
+        }
+        
+        for(j = 0; j < nv; j++){
+            
+            if(!V[j].processed && w[ver][j]){
+                relax(w,ver,j);
+               
+            }
+           
+        }
+        V[ver].processed = 1;
+        
+    }
+}
+
+void printPath(int src,int dest){
+    if(dest == src){
+        printf("\n%d", src);
+        return;
+    }
+    printPath(src,V[dest].par);
+    printf(" ------> %d",dest);
+
+}
+int main(){
+    int i,j,src,dest;
+    int w[size][size];
+    printf("ENTER NO. OF VERTICES \n");
+    scanf("%d",&nv);
+
+    printf("\nENTER THE WEIGHT MATRIX \n");
+    for(i = 0; i < nv; i++)
+    {
+        for(j = 0; j < nv; j++)
+        {
+            scanf("%d",&w[i][j]);
+        }
+    }
+    printf("\nENTER THE SOURCE \n");
+    scanf("%d",&src);
+    dijkstra(w,src);
+    do{
+        printf("\nENTER THE DESTINATION (ENTER -1 TO QUIT) \n");
+        scanf("%d",&dest);
+        if(dest != -1 && dest < nv){
+            printf("\nSHORTEST PATH WEIGHT = %d\n",V[dest].dist);
+            printf("\nPATH %d to %d IS",src,dest);
+            printPath(src,dest);
+        }
+    }while(dest != -1 && dest < nv);
+    return 0;
+}
+