题解 | #DNA序列#
DNA序列
http://www.nowcoder.com/practice/e8480ed7501640709354db1cc4ffd42a
str1 = input()
num = int(input())
max_str = [0,0]
if len(str1)-num> 0:
for i in range(len(str1)-num):
son_str = str1[i:i+num]
if (son_str.count('C')+son_str.count('G'))/num > max_str[0]:
max_str[0] = (son_str.count('C')+son_str.count('G'))/num
max_str[1] = son_str
print(max_str[1])
else:
print(str1)
