从 第3章-8 字符串逆序 开始
1.
n = str(input()) n1=n[::-1] print(n1)
2.
不是很好做这道题，自己还是C语言的思维，网上几乎也找不到什么答案
s = input() idx = s.find("#") s = s[:idx] ss = s[:idx] s_16 = "0123456789ABCDEFabcdef"
for c in s: if c not in s_16: s = s.replace(c, '') flag = 0 for c in ss: if c in s_16: flag = ss.find(c) break
if '-' in ss[:flag]: s = '-' + s if len(s) == 0: num_10 = 0 else: num_10 = int(s, 16) print(num_10)
3.
滤掉5个字母，还有空格和感叹号
a=input() count=0 for i in range(0,len(a)): if(a[i]!='A' and a[i]!='E' and a[i]!='I' and a[i]!='O' and a[i]!='U' and a[i]!='!' and a[i]!=' ' and 'A'<=a[i]<='Z'): count=count+1
print(count)
4.
我还在思考字符串怎么排序，发现其实之前做过的sort()函数可以用来无差别排序，一下子就简单了：
ls =list(input().split()) ls1=sorted(ls) print("After sorted") for i in ls1: print(i)