Python代码

from collections import deque
g=[]
for i in range(4):
    g.append(list(input()))
ans=deque()
tmp=deque()
def turn_one(x,y):
    g[x][y]='+' if g[x][y]=='-' else '-'
def turn_all(x,y):
    turn_one(x,y)
    for i in range(4):
        turn_one(x,i)
        turn_one(i,y)
def dfs(x,y):
    global ans,tmp
    if x==3 and y==4:
        success=True
        for i in range(4):
            for j in range(4):
                if g[i][j]=='+':
                    success=False
                    break
        if success :
            if  len(ans)<len(tmp):
                ans=tmp.copy()
        return
    if y==4:
        x+=1
        y=0
    #动开关
    tmp.append((x,y))
    turn_all(x,y)
    dfs(x,y+1)
    #恢复现场
    tmp.pop()
    turn_all(x,y)
    #不动开关
    dfs(x,y+1)
dfs(0,0)
print(len(ans))  # 输出最优解的长度
for i in range(len(ans)):
    step = ans[i]
    step = (step[0] + 1, step[1] + 1)  # 每个数字加 1
    print(step[0], step[1])  # 逐行输出最优解的步骤