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])