1、定义标记变量;利用变量值的变化退出循环
# 第一种嵌套形式
a = [[1, 2, 3], [5, 5, 6], [7, 8, 9]]
# init_i = 0
# init_j = 0
flag = True
for i in range(3):
for j in range(3):
# print(i, j)
if a[i][j] == 5:
flag = False
init_i = i
init_j = j
break
if not flag:
break
print(init_i, init_j)