Added matrix multiplication

algorithms/matrix/multiply.py

@@ -0,0 +1,28 @@
+"""
+You are given 2 matrices A and B
+first it checks if the 2 martrices can be multiplied
+if it can be multiplied it multiplies them in O(n^3) time
+"""
+
+def multiply(A: list,B: list)->list:
+    rowsA,rowsB=len(A),len(B)
+    colsA,colsB=len(A[0]),len(B[0])
+    if(colsA != rowsB):
+        raise Exception("Matrices cannot be multipled")
+
+    result=[[0 for i in range(colsB)] for j in range(rowsA)]#create a result matrix
+    for i in range(rowsA):
+        for j in range(colsB):
+            for k in range(len(B)):
+                result[i][j] += A[i][k] * B[k][j]
+    return result
+
+if __name__ == "__main__":
+    A = [[12, 7, 3],
+        [4, 5, 6],
+        [7, 8, 9]]
+    B = [[5, 8, 1, 2],
+        [6, 7, 3, 0],
+        [4, 5, 9, 1]]
+    import pprint
+    pprint.pprint(multiply(A,B))