如下代码中，语句if i == 0 and j == 0:和语句elif j == 0:难道不冲突吗？j == 0的情况也包含中i == 0 and j == 0吧？
size = int(input("请输入棋盘的大小："))
for i in range(size):
for j in range(size):
if i == 0 and j == 0:
print("┏",end='')
elif i == 0 and j == size - 1:
print("┓",end='')
elif i == size - 1 and j == 0:
print("┗",end='')
elif i == size - 1 and j == size - 1:
print("┛",end='')
elif j == 0:
print("┠",end='')
elif i == size - 1:
print("┷",end='')
elif j == size - 1:
print("┨",end='')
elif i == 0:
print("┯",end='')
else:
print("┼",end='')
print('')
不冲突的，如果只是i ==0满足条件，但是j不满足条件的话，不会执行if，执行的是elif i==0
size = int(input("请输入棋盘的大小："))
for i in range(size):
for j in range(size):
if i == 0 and j == 0:
print("┏",end='')
elif j == 0:
print("┠",end='')
elif i == 0:
print("┯",end='')
else:
print("┼",end='')
print('')
分析一下有疑问的分支。
1)当i =0,j不等于0时，执行elif i == 0:分支
1)当i 不等于0,j=0时，执行elif j == 0:分支
1)当i =0,j=0时，执行if i == 0 and j == 0分支
and是同时满足多个条件，如果换成or就冲突了