Spiral

cpp/matrix/AdjacencyMatrix.cpp

@@ -0,0 +1,62 @@
+// Adjacency Matrix representation in C++
+
+#include <iostream>
+using namespace std;
+
+class Graph {
+   private:
+  bool** adjMatrix;
+  int numVertices;
+
+   public:
+  // Initialize the matrix to zero
+  Graph(int numVertices) {
+    this->numVertices = numVertices;
+    adjMatrix = new bool*[numVertices];
+    for (int i = 0; i < numVertices; i++) {
+      adjMatrix[i] = new bool[numVertices];
+      for (int j = 0; j < numVertices; j++)
+        adjMatrix[i][j] = false;
+    }
+  }
+
+  // Add edges
+  void addEdge(int i, int j) {
+    adjMatrix[i][j] = true;
+    adjMatrix[j][i] = true;
+  }
+
+  // Remove edges
+  void removeEdge(int i, int j) {
+    adjMatrix[i][j] = false;
+    adjMatrix[j][i] = false;
+  }
+
+  // Print the martix
+  void toString() {
+    for (int i = 0; i < numVertices; i++) {
+      cout << i << " : ";
+      for (int j = 0; j < numVertices; j++)
+        cout << adjMatrix[i][j] << " ";
+      cout << "\n";
+    }
+  }
+
+  ~Graph() {
+    for (int i = 0; i < numVertices; i++)
+      delete[] adjMatrix[i];
+    delete[] adjMatrix;
+  }
+};
+
+int main() {
+  Graph g(4);
+
+  g.addEdge(0, 1);
+  g.addEdge(0, 2);
+  g.addEdge(1, 2);
+  g.addEdge(2, 0);
+  g.addEdge(2, 3);
+
+  g.toString();
+}

cpp/matrix/MatrixAdd.cpp

@@ -0,0 +1,49 @@
+#include <iostream>
+using namespace std;
+
+int main()
+{
+    int r, c, a[100][100], b[100][100], sum[100][100], i, j;
+
+    cout << "Enter number of rows (between 1 and 100): ";
+    cin >> r;
+
+    cout << "Enter number of columns (between 1 and 100): ";
+    cin >> c;
+
+    cout << endl << "Enter elements of 1st matrix: " << endl;
+
+    // Storing elements of first matrix entered by user.
+    for(i = 0; i < r; ++i)
+       for(j = 0; j < c; ++j)
+       {
+           cout << "Enter element a" << i + 1 << j + 1 << " : ";
+           cin >> a[i][j];
+       }
+
+    // Storing elements of second matrix entered by user.
+    cout << endl << "Enter elements of 2nd matrix: " << endl;
+    for(i = 0; i < r; ++i)
+       for(j = 0; j < c; ++j)
+       {
+           cout << "Enter element b" << i + 1 << j + 1 << " : ";
+           cin >> b[i][j];
+       }
+
+    // Adding Two matrices
+    for(i = 0; i < r; ++i)
+        for(j = 0; j < c; ++j)
+            sum[i][j] = a[i][j] + b[i][j];
+
+    // Displaying the resultant sum matrix.
+    cout << endl << "Sum of two matrix is: " << endl;
+    for(i = 0; i < r; ++i)
+        for(j = 0; j < c; ++j)
+        {
+            cout << sum[i][j] << "  ";
+            if(j == c - 1)
+                cout << endl;
+        }
+
+    return 0;
+}

cpp/matrix/MatrixSub.cpp

@@ -0,0 +1,49 @@
+#include <iostream>
+using namespace std;
+
+int main()
+{
+    int r, c, a[100][100], b[100][100], sum[100][100], i, j;
+
+    cout << "Enter number of rows (between 1 and 100): ";
+    cin >> r;
+
+    cout << "Enter number of columns (between 1 and 100): ";
+    cin >> c;
+
+    cout << endl << "Enter elements of 1st matrix: " << endl;
+
+    // Storing elements of first matrix entered by user.
+    for(i = 0; i < r; ++i)
+       for(j = 0; j < c; ++j)
+       {
+           cout << "Enter element a" << i + 1 << j + 1 << " : ";
+           cin >> a[i][j];
+       }
+
+    // Storing elements of second matrix entered by user.
+    cout << endl << "Enter elements of 2nd matrix: " << endl;
+    for(i = 0; i < r; ++i)
+       for(j = 0; j < c; ++j)
+       {
+           cout << "Enter element b" << i + 1 << j + 1 << " : ";
+           cin >> b[i][j];
+       }
+
+    // Subtracting Two matrices
+    for(i = 0; i < r; ++i)
+        for(j = 0; j < c; ++j)
+            sum[i][j] = a[i][j] - b[i][j];
+
+    // Displaying the resultant sum matrix.
+    cout << endl << "Sum of two matrix is: " << endl;
+    for(i = 0; i < r; ++i)
+        for(j = 0; j < c; ++j)
+        {
+            cout << sum[i][j] << "  ";
+            if(j == c - 1)
+                cout << endl;
+        }
+
+    return 0;
+}

cpp/matrix/matrixMul.cpp

@@ -0,0 +1,48 @@
+#include <iostream>  
+using namespace std;  
+int main()  
+{  
+int a[10][10],b[10][10],mul[10][10],r,c,i,j,k;    
+cout<<"enter the number of row=";    
+cin>>r;    
+cout<<"enter the number of column=";    
+cin>>c;    
+cout<<"enter the first matrix element=\n";    
+for(i=0;i<r;i++)    
+{    
+for(j=0;j<c;j++)    
+{    
+cin>>a[i][j];  
+}    
+}    
+cout<<"enter the second matrix element=\n";    
+for(i=0;i<r;i++)    
+{    
+for(j=0;j<c;j++)    
+{    
+cin>>b[i][j];    
+}    
+}    
+cout<<"multiply of the matrix=\n";    
+for(i=0;i<r;i++)    
+{    
+for(j=0;j<c;j++)    
+{    
+mul[i][j]=0;    
+for(k=0;k<c;k++)    
+{    
+mul[i][j]+=a[i][k]*b[k][j];    
+}    
+}    
+}    
+//for printing result    
+for(i=0;i<r;i++)    
+{    
+for(j=0;j<c;j++)    
+{    
+cout<<mul[i][j]<<" ";    
+}    
+cout<<"\n";    
+}    
+return 0;  
+}

cpp/matrix/spiralMatrix.cpp

@@ -0,0 +1,59 @@
+// C++ program for the above approach
+
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<int> spiralOrder(vector<vector<int> >& matrix)
+{
+	int m = matrix.size(), n = matrix[0].size();
+	vector<int> ans;
+
+	if (m == 0)
+		return ans;
+
+	vector<vector<bool> > seen(m, vector<bool>(n, false));
+	int dr[] = { 0, 1, 0, -1 };
+	int dc[] = { 1, 0, -1, 0 };
+
+	int x = 0, y = 0, di = 0;
+
+	// Iterate from 0 to m * n - 1
+	for (int i = 0; i < m * n; i++) {
+		ans.push_back(matrix[x][y]);
+		// on normal geeksforgeeks ui page it is showing
+		// 'ans.push_back(matrix[x])' which gets copied as
+		// this only and gives error on compilation,
+		seen[x][y] = true;
+		int newX = x + dr[di];
+		int newY = y + dc[di];
+
+		if (0 <= newX && newX < m && 0 <= newY && newY < n
+			&& !seen[newX][newY]) {
+			x = newX;
+			y = newY;
+		}
+		else {
+			di = (di + 1) % 4;
+			x += dr[di];
+			y += dc[di];
+		}
+	}
+	return ans;
+}
+
+// Driver code
+int main()
+{
+	vector<vector<int> > a{ { 1, 2, 3, 4 },
+							{ 5, 6, 7, 8 },
+							{ 9, 10, 11, 12 },
+							{ 13, 14, 15, 16 } };
+
+	// Function call
+	for (int x : spiralOrder(a)) {
+		cout << x << " ";
+	}
+	return 0;
+}
+
+// This code is contributed by Yashvendra Singh

java/matrix/AdjMatrix.java

@@ -0,0 +1,49 @@
+// Adjacency Matrix representation in Java
+
+public class Graph {
+  private boolean adjMatrix[][];
+  private int numVertices;
+
+  // Initialize the matrix
+  public Graph(int numVertices) {
+    this.numVertices = numVertices;
+    adjMatrix = new boolean[numVertices][numVertices];
+  }
+
+  // Add edges
+  public void addEdge(int i, int j) {
+    adjMatrix[i][j] = true;
+    adjMatrix[j][i] = true;
+  }
+
+  // Remove edges
+  public void removeEdge(int i, int j) {
+    adjMatrix[i][j] = false;
+    adjMatrix[j][i] = false;
+  }
+
+  // Print the matrix
+  public String toString() {
+    StringBuilder s = new StringBuilder();
+    for (int i = 0; i < numVertices; i++) {
+      s.append(i + ": ");
+      for (boolean j : adjMatrix[i]) {
+        s.append((j ? 1 : 0) + " ");
+      }
+      s.append("\n");
+    }
+    return s.toString();
+  }
+
+  public static void main(String args[]) {
+    Graph g = new Graph(4);
+
+    g.addEdge(0, 1);
+    g.addEdge(0, 2);
+    g.addEdge(1, 2);
+    g.addEdge(2, 0);
+    g.addEdge(2, 3);
+
+    System.out.print(g.toString());
+  }
+}

java/matrix/Identity.java

@@ -0,0 +1,44 @@
+public class IdentityMatrix     
+{    
+    public static void main(String[] args) {    
+        int rows, cols;    
+        boolean flag = true;    
+
+        //Initialize matrix a    
+        int a[][] = {       
+                        {1, 0, 0},    
+                        {0, 1, 0},    
+                        {0, 0, 1}    
+                    };    
+
+        //Calculates the number of rows and columns present in the given matrix    
+
+          rows = a.length;    
+        cols = a[0].length;    
+
+        //Checks whether given matrix is a square matrix or not    
+        if(rows != cols){    
+            System.out.println("Matrix should be a square matrix");    
+        }    
+        else {    
+            //Checks if diagonal elements are equal to 1 and rest of elements are 0    
+            for(int i = 0; i < rows; i++){    
+                for(int j = 0; j < cols; j++){    
+                  if(i == j && a[i][j] != 1){    
+                      flag = false;    
+                      break;    
+                  }    
+                  if(i != j && a[i][j] != 0){    
+                      flag = false;    
+                      break;    
+                  }    
+                }    
+            }    
+
+            if(flag)    
+                System.out.println("Given matrix is an identity matrix");    
+            else    
+                System.out.println("Given matrix is not an identity matrix");    
+        }    
+    }    
+}    

java/matrix/MatrixAddition.java

@@ -0,0 +1,18 @@
+public class MatrixAdditionExample{  
+public static void main(String args[]){  
+//creating two matrices    
+int a[][]={{1,3,4},{2,4,3},{3,4,5}};    
+int b[][]={{1,3,4},{2,4,3},{1,2,4}};    
+
+//creating another matrix to store the sum of two matrices    
+int c[][]=new int[3][3];  //3 rows and 3 columns  
+
+//adding and printing addition of 2 matrices    
+for(int i=0;i<3;i++){    
+for(int j=0;j<3;j++){    
+c[i][j]=a[i][j]+b[i][j];    //use - for subtraction  
+System.out.print(c[i][j]+" ");    
+}    
+System.out.println();//new line    
+}    
+}}