题解 | #DNA序列#python3

字符串的索引，注意输出的长度和字符串长度相等的情况

while True:
    try:
        str1 = str(input())
        num1 = int(input())

        mark = 0
        tstr = ''

        if(len(str1) == num1):
            print(str1)
        else:
            for i in range(len(str1)-num1):
                k = 0
                for j in range(i,i+num1):
                    if(str1[j] == 'C' or str1[j] == 'G'):
                        k += 1
                if(k > mark):
                    mark = k
                    tstr = ''
                    for l in range(i,i+num1):
                        tstr += str1[l]
        print(tstr)
    except:
        break