经典回溯算法之八皇后问题 -- Python

# -*- coding: UTF-8 -*-
import copy 

# 使用全局变量保存结果
global arr 
global count
global mlist

# 定义条件判定函数
def conflict(index,col):
	global arr
	for i in range(index):
		if arr[i][col] == 1:
			return True
		for j in range(8):
			if arr[i][j] == 1 and abs(i-index) == abs(j-col):
				return True
	return False

# 递归查找函数
def find(index):
	global count, arr,mlist
	if index == 8:  # 结束条件
		count += 1
		mlist.append(copy.deepcopy(arr))
	else:
		for i in range(8): # 穷举所有可能
			if not conflict(index,i):
				arr[index][i] = 1 # 设置当前完成步骤
				find(index+1)     # 继续探索剩余步骤
				arr[index][i] = 0 # 恢复原貌
		
if __name__ == "__main__":
	global count,arr
	# 初始化
	arr = [[0]*8 for i in range(8)] # 棋盘
	count = 0
	mlist = []
	
	find(0) # 开始计算
	
	# 打印结果
	print(count)
	for k in range(count):
		print("-----------------------------")
		for i in range(8):
			print(mlist[k][i])