Complementing a Strand of DNA

Problem

In DNA strings, symbols 'A'
and 'T' are complements of each other, as are 'C' and 'G'.

The reverse
complement of a DNA string is
the string formed
by reversing the symbols of ,
then taking the complement of each symbol (e.g., the reverse complement of "GTCA" is "TGAC").

Given: A DNA string of
length at most 1000 bp.

Return: The reverse complement of .

Sample Dataset

AAAACCCGGT

Sample Output

ACCGGGTTTT
翻译，用了一个hash表来弄，比if，switch什么的好用。

file=open('rosalind_revc.txt','r');
seq=file.read();
print(seq)
leng=len(seq);
tran={'A':'T','T':'A','C':'G','G':'C'};
trna=[];
for i in range(0,leng):
trna.append(tran[seq[leng-1-i]]);
trna_convert=''.join(trna);
f=open('out3.txt','w')
f.write(trna_convert)
f.close

注意：每次用下载的txt都会出现keyerror，是因为我不是按行读取的，直接把文件全部读入，文件最后提行了。多了个\n

list还要先定义，write的时候不能直接是list，不知道怎么写，就把list转成str了，trna_convert=''.join(trna)