题解 | #DNA序列#
DNA序列
https://www.nowcoder.com/practice/e8480ed7501640709354db1cc4ffd42a
s = input()
n = int(input())
dic = {}
GC = 0
for i in range(len(s)):
GC = s[i:i+n].count("G") + s[i:i+n].count("C")
dic[s[i:i+n]] = GC
max = max(dic.values())
for i in dic:
if dic[i] == max:
print(i)
break
