Added dijkstras algorithm in C++ (#937)

Signed-off-by: Mayuri Kothari <115354882+MAYURIKOTHARI299@users.noreply.github.com>

Author: MAYURIKOTHARI299

C++/Algorithms/GreedyAlgorithms/dijkstra.cpp

@@ -0,0 +1,65 @@
+#include <iostream>
+
+using namespace std;
+
+int miniDist(int distance[], bool Tset[],int m,int n) // finding minimum distance
+{
+    int minimum=INT_MAX,ind;
+
+    for(int k=0;k<m;k++)
+    {
+        if(Tset[k]==false && distance[k]<=minimum)
+        {
+            minimum=distance[k];
+            ind=k;
+        }
+    }
+    return ind;
+}
+
+void DijkstraAlgo(int m, int n,int graph[][20],int src) // adjacency matrix
+{
+    int distance[m]; // // array to calculate the minimum distance for each node
+    bool Tset[n];// boolean array to mark visited and unvisited for each node
+
+
+    for(int k = 0; k<m; k++)
+    {
+        distance[k] = INT_MAX;
+        Tset[k] = false;
+    }
+
+    distance[src] = 0;   // Source vertex distance is set 0
+
+    for(int k = 0; k<m; k++)
+    {
+        int mn=miniDist(distance,Tset,m,n);
+        Tset[mn]=true;
+        for(int k = 0; k<m; k++)
+        {
+            // updating the distance of neighbouring vertex
+            if(!Tset[k] && graph[mn][k] && distance[mn]!=INT_MAX && distance[mn]+graph[mn][k]<distance[k])
+                distance[k]=distance[mn]+graph[mn][k];
+        }
+    }
+    cout<<"Vertex\t\tDistance from source vertex"<<endl;
+    for(int k = 0; k<m; k++)
+    {
+        char str=65+k;
+        cout<<str<<"\t\t\t"<<distance[k]<<endl;
+    }
+}
+
+int main()
+
+{ int m,n;
+cin>>m>>n;
+    int graph[20][20];
+    for(int i=0;i<m;i++){
+        for(int j=0;j<m;j++){
+            cin>>graph[i][j];
+        }
+    }
+    DijkstraAlgo(m,n,graph,0);
+    return 0;
+}