Create NQueenProblem.cpp

Author: namishagoel

Backtracking/NQueenProblem.cpp

@@ -0,0 +1,73 @@
+#define N 4 
+#include <stdbool.h> 
+#include <stdio.h> 
+
+
+void printSolution(int board[N][N]) 
+{ 
+	for (int i = 0; i < N; i++) { 
+		for (int j = 0; j < N; j++) 
+			printf(" %d ", board[i][j]); 
+		printf("\n"); 
+	} 
+} 
+
+bool isSafe(int board[N][N], int row, int col) 
+{ 
+	int i, j; 
+
+	for (i = 0; i < col; i++) 
+		if (board[row][i]) 
+			return false; 
+	for (i = row, j = col; i >= 0 && j >= 0; i--, j--) 
+		if (board[i][j]) 
+			return false; 
+
+		for (i = row, j = col; j >= 0 && i < N; i++, j--) 
+		if (board[i][j]) 
+			return false; 
+
+	return true; 
+} 
+
+bool solveNQUtil(int board[N][N], int col) 
+{ 
+	if (col >= N) 
+		return true; 
+
+
+	for (int i = 0; i < N; i++) { 
+		if (isSafe(board, i, col)) { 
+			board[i][col] = 1; 
+			if (solveNQUtil(board, col + 1)) 
+				return true; 
+
+			board[i][col] = 0;
+		} 
+	} 
+	return false; 
+} 
+
+
+bool solveNQ() 
+{ 
+	int board[N][N] = { { 0, 0, 0, 0 }, 
+						{ 0, 0, 0, 0 }, 
+						{ 0, 0, 0, 0 }, 
+						{ 0, 0, 0, 0 } }; 
+
+	if (solveNQUtil(board, 0) == false) { 
+		printf("Solution does not exist"); 
+		return false; 
+	} 
+
+	printSolution(board); 
+	return true; 
+} 
+
+
+int main() 
+{ 
+	solveNQ(); 
+	return 0; 
+}