Write a Python code for N Queen Problem where N=8 code example
Example: print all possible solution for n-queen problem in python
### This code prints all possible solution for Nqueen problem
# Function to check if two queens threaten each other or not
def isSafe(mat, r, c):
# return false if two queens share the same column
for i in range(r):
if mat[i][c] == 'Q':
return False
# return false if two queens share the same `` diagonal
(i, j) = (r, c)
while i >= 0 and j >= 0:
if mat[i][j] == 'Q':
return False
i = i - 1
j = j - 1
# return false if two queens share the same `/` diagonal
(i, j) = (r, c)
while i >= 0 and j < N:
if mat[i][j] == 'Q':
return False
i = i - 1
j = j + 1
return True
def printSolution(mat):
for i in range(N):
print(mat[i])
print()
def nQueen(mat, r):
# if `N` queens are placed successfully, print the solution
if r == N:
printSolution(mat)
return
# place queen at every square in the current row `r`
# and recur for each valid movement
for i in range(N):
# if no two queens threaten each other
if isSafe(mat, r, i):
# place queen on the current square
mat[r][i] = 'Q'
# recur for the next row
nQueen(mat, r + 1)
# backtrack and remove the queen from the current square
mat[r][i] = '–'
if __name__ == '__main__':
# `N × N` chessboard
N = 8
# `mat[][]` keeps track of the position of queens in
# the current configuration
mat = [['–' for x in range(N)] for y in range(N)]
nQueen(mat, 0)