gistfile1.txt

def same_row(x, y, grid):
    for j in xrange(9):
        if j != y and grid[x][j] != '0':
            yield grid[x][j]

def same_column(x, y, grid):
    for i in xrange(9):
        if i != x and grid[i][y] != '0':
            yield grid[i][y]

def same_box(x, y, grid):
    coords = x, y
    candidates = [[], []]
    for i in xrange(2):
        if not coords[i] % 3:
            candidates[i] = coords[i], coords[i] + 1, coords[i] + 2
        elif coords[i] % 3 == 1:
            candidates[i] = coords[i] - 1, coords[i], coords[i] + 1
        else:
            candidates[i] = coords[i] - 2, coords[i] - 1, coords[i]
    for i in candidates[0]:
        for j in candidates[1]:
            if (i, j) != (x, y) and grid[i][j] != '0':
                yield grid[i][j]

def valid(x, y, d, grid):
    if d in same_row(x, y, grid) or d in same_column(x, y, grid) or d in same_box(x, y, grid):
        return False
    return True

def solve(grid, x, y):
    if x == 9:
        return True
    next_x = x
    next_y = y + 1
    if y == 8:
        next_x = x + 1
        next_y = 0
    if grid[x][y] != '0':
        return solve(grid, next_x, next_y)
    for d in '123456789':
        grid[x][y] = d
        if valid(x, y, d, grid):
            if solve(grid, next_x, next_y):
                return True
    grid[x][y] = '0'
    return False

fp = open('sudoku.txt')
contents = fp.read()
fp.close()

total = 0

for line in contents.splitlines():
    if line.startswith('G'):
        grid = [[0 for x in xrange(9)] for y in xrange(9)]
        i = 0
    else:
        for j, d in enumerate(line):
            grid[i][j] = d
        i += 1
        if i == 9:
            solve(grid, 0, 0)
            total += int(grid[0][0]) * 100 + int(grid[0][1]) * 10 + int(grid[0][2])

print total