8 Queens using BackTracking in Python using JSON file as Input

Input

The input to the program is the position of the first queen which taken from a json file.

Code

import json

def safe(row,col,board):
 for i in range(row):
  if board[i][col]==1:
   return False

 i=row-1
 j=col-1

 while i>=0 and j>=0:
  if board[i][j]==1:
   return False
  i-=1
  j-=1
 
 i=row-1
 j=col+1

 while i>=0 and j<=7:
  if board[i][j]==1:
   return False
  i-=1
  j+=1

 return True


def solve(board,row):
 col=0
 if row==8:
  return True
 while col<=7:
  if safe(row,col,board):
   board[row][col]=1
   if solve(board,row+1):
    return True
   else:
    board[row][col]=0


  col+=1
 return False


def pboard(board):
 for i in range(8):
  for j in range(8):
   print board[i][j],
  print
  
with open('input.json') as f:
 data=json.load(f)
board=[[0 for x in range (8)] for y in range (8)]
board[0][int(data["start"])]=1


if(solve(board,1)):
 print "Solved"
 pboard(board) 
else:
 print "Failed to Solve"

input.json

{"start":0}

Output

[duke@duke-pc b1]$ python2 q.py
Solved
1 0 0 0 0 0 0 0
0 0 0 0 1 0 0 0
0 0 0 0 0 0 0 1
0 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0
0 0 0 0 0 0 1 0
0 1 0 0 0 0 0 0
0 0 0 1 0 0 0 0