Merge pull request #451 from mirajkarsaurabh/mirajkarsaurabh-patch-1

Added Strassens Algorithm

Author: amritansh22

Strassen’s Algorithm.cpp

@@ -0,0 +1,83 @@
+#include <iostream>
+using namespace std;
+void multiply(int[5][5], int[5][5], int, int, int);
+int display(int[5][5], int, int);
+int main()
+{
+
+   int a[5][5], b[5][5], r1, c1, r2, c2;
+   cout<<"\n Enter rows for first matrix: ";
+    cin>>r1;
+   cout<<"\n Enter columns for second matrix: ";
+     cin>>c1;
+
+   cout<<"\n Enter rows for first matrix: ";
+     cin>>r2;
+   cout<<"\n Enter columns for second matrix: ";
+      cin>>c2;
+
+  // To check if columns of first matrix are equal to rows of second matrix
+
+   if (c1 != r2)
+        return 0;
+
+   // Storing elements of first matrix.
+
+   cout<<"\n Enter elements of first matrix \n";
+
+   for(int i=0; i<r1; i++)
+    {
+       for(int j=0; j<c1; j++)
+           cin>>a[i][j];
+
+    }
+   // Storing elements of second matrix.
+    cout<<"\n Enter elements of second matrix\n";
+
+   for(int i=0; i<r2; i++)
+    {
+       for(int j=0; j<c2; j++)
+           cin>>b[i][j];
+    }
+    display(a,r1,c1);
+    display(b,r2,c2);
+    //calling the function to multiply a and b. passing number of rows
+    //and columns in both of them
+   multiply(a, b, r1, c2, c1);
+   return 0;
+}
+
+void multiply(int a[5][5], int b[5][5], int row, int col, int c1)
+{
+   int c[5][5];
+    //input 0 for all values of c, in order to remove
+    //the garbage values assigned earlier
+    for(int i=0; i<row; i++)
+    {
+       for(int j=0; j<col; j++)
+           c[i][j]=0;
+    }
+    //we apply the same formula as above
+   for(int i=0; i<row; i++)
+    {
+       for(int j=0; j<col; j++)
+        {
+           for(int k=0; k<c1; k++)//columns of first matrix || rows of second matrix
+                  c[i][j]+=a[i][k]*b[k][j];
+        }
+    }
+    //to display matrix
+ cout<<"\n Matrix c after matrix multiplication is:\n";
+  display(c, row, col);
+}
+int display(int c[5][5], int row, int col)
+{
+   cout<<"\n Matrix is:\n";
+   for(int i=0; i<row; i++)
+   {
+       for(int j=0; j<col; j++)
+            cout<<c[i][j]<<" ";
+        cout<<"\n";
+    }
+    return 0;
+}