题解 | #DNA序列#

• 这代码里还是很多坑的

s = input()
n = int(input())

idx, cnt, max_cnt = 0, 0, 0
for i, ch in enumerate(s):
    if i >= n and (s[i-n] == 'C' or s[i-n] == 'G'):
        cnt -= 1
    if ch == 'G' or ch == 'C':
        cnt += 1
    # 确保字串长度等于n
    if i >= n - 1 and max_cnt < cnt:
        idx = i
        max_cnt = cnt
print(s[(idx - n + 1):idx+1])