N Queen Problem

Backtracking/N Queens.cpp

@@ -0,0 +1,82 @@
+#include<iostream>
+#define N 4
+using namespace std;
+
+void printSolution(int board[N][N])
+{
+    cout<<"\n";
+    for (int i = 0; i < N; i++)
+    {
+        for (int j = 0; j < N; j++)
+            cout<<""<<board[i][j];
+        cout<<"\n";
+    }
+}
+ 
+
+bool isSafe(int board[N][N], int row, int col)
+{
+    int i, j;
+ 
+    /* Check this row on left side */
+    for (i = 0; i < col; i++)
+        if (board[row][i])
+            return false;
+ 
+    /* Check upper diagonal on left side */
+    for (i=row, j=col; i>=0 && j>=0; i--, j--)
+        if (board[i][j])
+            return false;
+ 
+    /* Check lower diagonal on left side */
+    for (i=row, j=col; j>=0 && i<N; i++, j--)
+        if (board[i][j])
+            return false;
+ 
+    return true;
+}
+ 
+
+void solveNQ(int board[N][N], int col)
+{
+    
+    if (col >= N){
+        printSolution(board);
+        return;
+    }
+ 
+    /* Consider this column and try placing
+       this queen in all rows one by one */
+    for (int i = 0; i < N; i++)
+    {
+        /* Check if queen can be placed on
+          board[i][col] */
+        if ( isSafe(board, i, col) )
+        {
+            /* Place this queen in board[i][col] */
+//            cout<<"\n"<<col<<"can place"<<i;
+            board[i][col] = 1;
+ 
+            /* recur to place rest of the queens */
+            solveNQ(board, col + 1);
+                
+
+            board[i][col] = 0; // BACKTRACK
+        }
+    }
+ 
+}
+ 
+ 
+int main()
+{
+    
+   int board[N][N] = { {0, 0, 0, 0},
+       {0, 0, 0, 0},
+       {0, 0, 0, 0},
+       {0, 0, 0, 0}
+   };
+   
+	solveNQ(board, 0);
+    return 0;
+}

Strassen Matrix Multiplication.cpp

@@ -0,0 +1,60 @@
+#include <iostream>
+using namespace std;
+
+Multiply(int A[][], int B[][], int n)
+{
+	if (n==2)
+	{
+		int p1= (a[0][0] + a[1][1])*(b[0][0]+b[1][1]);
+	  	int p2= (a[1][0]+a[1][1])*b[0][0];
+	 	int p3= a[0][0]*(b[0][1]-b[1][1]);
+	 	int p4= a[1][1]*(b[1][0]-b[0][0]);
+	 	int p5= (a[0][0]+a[0][1])*b[1][1];
+	 	int p6= (a[1][0]-a[0][0])*(b[0][0]+b[0][1]);
+	 	int p7= (a[0][1]-a[1][1])*(b[1][0]+b[1][1]);
+
+
+	 	int c[n][n];
+		c[0][0]=p1+p4-p5+p7;
+ 		c[0][1]=p3+p5;
+ 		c[1][0]=p2+p4;
+ 		c[1][1]=p1-p2+p3+p6;
+
+ 	 	return c[][];
+	}
+	else
+	{
+		
+	}
+
+}
+
+int main()
+{
+	int p,q,r,s;
+	cout<<"Enter the dimensions of Matrices";
+	cin>>n;
+	int A[n][n],;
+	int B[n][n],;
+	cout<<"Enter the elements of Matrix A";
+	for (int i = 0; i < n; i++)
+	{
+		for (int j = 0; j <n ; j++)
+		{
+			cin>>A[i][j];
+		}
+	}
+
+
+	cout<<"Enter the elements of Matrix B";
+	for (int i = 0; i < n; i++)
+	{
+		for (int j = 0; j <n ; j++)
+		{
+			cin>>B[i][j];
+		}
+	}
+
+	Multiply(A, B, n);
+	return 0;
+}