s=input("输入字符串:")
n=len(s)
i,j=0,n-1
result=""
while i<n//2 and j>=n//2:
if s[i]>s[j]:
result+=s[i]; j-=1
elif s[i] < s[j]:
result+=s[j]; i+=1
else:
i+=1;j-=1
print(result)
执行该程序段,分别输入下列选项中的字符串,输出结果不为“555”的是( )
A."51234" | B."12535" | C."54321" | D."55123" |
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