题解 | DNA序列

import sys

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

temp = s[0:n]
count = 0
for _ in temp:
    if _ in {'C','G'}:
        count+=1

max_s = 0
max_count = count
#print(max_s,max_count)
for i in range(n,len(s)):
    #print(i,s[i])
    #print(s[i],s[i-n])
    if s[i-n] in {'C','G'}:
        count -= 1
    if s[i] in {'C','G'}:
        count+=1
        if count > max_count:
            max_count = count
            max_s = i-n+1
            #print(max_count)
print(s[max_s:max_s+n])
    

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记个数就行