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| class Solution(object):
count = 0
def dfs(self, n, depth, diag1, diag2, visited):
if n == depth:
self.count += 1
return
x = depth
for y in xrange(n):
if not visited[y] and not diag1[x + y] and not diag2[x - y + n - 1]:
visited[y] = True
diag1[x + y] = True
diag2[x - y + n - 1] = True
self.dfs(n, depth + 1, diag1, diag2, visited)
visited[y] = False
diag1[x + y] = False
diag2[x - y + n - 1] = False
def totalNQueens(self, n):
"""
:type n: int
:rtype: int
"""
if n == 0:
return 0
diag1 = [False] * (2 * n - 1)
diag2 = [False] * (2 * n - 1)
visited = [False] * n
self.dfs(n, 0, diag1, diag2, visited)
return self.count
|