a={'<':0, '()':1, '[': 2, '{':3, '>': 4, ') ':5, '] ':6, '} ':7}
s1=input()
s=[8,0,0,0,0,0,0,0,0]
top=0; flag=True
for x in s1:
k=a[x]
if k<4:
if s[top]!=k:
flag=False
break
top+=1
s[top] =k
else:
if s[top]!=k-4:
flag=False
break
top-=1
if flag and top==0:
print ("YES")
else:
print ("NO")
若输出结果为“NO”,则s1输入的值是( )
A.{} []() <> | B.[()]{<>} | C.{[<()>]} | D.{()[<>]} |
同类型试题
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
y = sin x, x∈R, y∈[–1,1],周期为2π,函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x, x∈[–1,1], y∈[–π/2,π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2