Nqueens

Nqueens.py

@@ -0,0 +1,54 @@
+n=int(input('Enter number of queens:'))
+def solveNQueens(n):
+    # Initialize the board as a 2D list of zeros
+    board = [[0 for _ in range(n)] for _ in range(n)]
+
+    def isSafe(row, col):
+        # Check if any queens already placed in the same row
+        for i in range(col):
+            if board[row][i] == 1:
+                return False
+
+        # Check if any queens already placed in the same upper diagonal
+        i, j = row, col
+        while i >= 0 and j >= 0:
+            if board[i][j] == 1:
+                return False
+            i -= 1
+            j -= 1
+
+        # Check if any queens already placed in the same lower diagonal
+        i, j = row, col
+        while i < n and j >= 0:
+            if board[i][j] == 1:
+                return False
+            i += 1
+            j -= 1
+
+        # If no conflicts found, then the position is safe
+        return True
+
+    def solveHelper(col):
+        # Base case: If all queens are placed, return True
+        if col == n:
+            return True
+
+        # Recursive case: Try placing queen in each row of current column
+        for row in range(n):
+            if isSafe(row, col):
+                board[row][col] = 1
+                if solveHelper(col + 1):
+                    return True
+                board[row][col] = 0
+
+        # If no safe position found, backtrack
+        return False
+
+    # Call the helper function to solve N-Queens problem
+    if solveHelper(0):
+        # Print the board
+        for row in board:
+            print(row)
+    else:
+        print("No solution exists for N =", n)
+solveNQueens(n)