Merge pull request #44 from nancy0119/issue#14

Added the code of  matrix multiplication

Author: unnati914

matrix Multiplication.java

@@ -0,0 +1,86 @@
+/*
+  MatrixMultiplication code helps in taking input as 2 matrices of any order and prints their product.
+*/
+
+import java.io.*;
+import java.util.*;
+
+public class matrixMultiplication{
+
+    public static void main(String[] args) throws Exception {
+      Scanner s = new Scanner(System.in);
+    //    Taking input as matrix1:
+        System.out.println("Enter the no. of rows of the first matrix:");
+        int row1 = s.nextInt();
+        System.out.println("Enter the no. of cols of the first matrix:");
+        int col1 = s.nextInt();
+        int[][] mat1 = new int[row1][col1];
+        System.out.println("Enter the elements of the first matrix:");
+        for (int i = 0; i < row1; i++) {
+            for (int j = 0; j < col1; j++) {
+                mat1[i][j] = s.nextInt();
+            }
+        }
+    //    Taking input as matrix2:
+        System.out.println("Enter the no. of rows of the second matrix:");
+        int row2 = s.nextInt();
+        System.out.println("Enter the no. of cols of the second matrix:");
+        int col2 = s.nextInt();
+        int[][] mat2 = new int[row2][col2];
+        System.out.println("Enter the elements of the second matrix:");
+        for (int i = 0; i < row2; i++) {
+            for (int j = 0; j < col2; j++) {
+                mat2[i][j] = s.nextInt();
+            }
+        }
+
+        if (col1 == row2) {
+            int ans[][] = matrixMul(mat1, mat2);
+            display(ans);
+        } else System.out.print("Invalid input");
+        s.close();
+    }
+
+    public static int[][] matrixMul(int[][] arr1, int[][] arr2) {
+        int[][] res = new int[arr1.length][arr2[0].length];
+        for (int i = 0; i < arr1.length; i++) {
+            for (int j = 0; j < arr2[0].length; j++) {
+                res[i][j] = 0;
+                for (int k = 0; k < arr1[0].length; k++) {
+                    res[i][j] += arr1[i][k] * arr2[k][j];
+                }
+            }
+        }
+        return res;
+    }
+    public static void display(int [][] mat){
+        for (int i=0;i<mat.length;i++){
+            for (int j=0;j<mat[0].length;j++){
+                System.out.print(mat[i][j] +" ");
+            }
+            System.out.println();
+        }
+    }
+
+    }
+
+    /*
+    Sample Input/Output:
+
+    Input:
+    2
+    2
+    1 2
+    3 4
+    2
+    2
+    5 6
+    7 8
+
+    Output:
+    19 22
+    43 50
+
+    Time Complexity:O(n^2)
+    Space Complexity:O(n)
+    */