题解 | #DNA序列#

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void async function () {
    const DNA = await readline();
    const k = parseInt(await readline());
    let cnt = 0,max = 0, start = 0;
    for(let i = 0; i < k; i++){
        if(DNA.charAt(i) === "C" || DNA.charAt(i) === "G") cnt ++;
    }
    max = cnt;
    for(let i = 1; i < DNA.length - k; i++){
        if(DNA.charAt(i-1) === "C" || DNA.charAt(i-1) === "G") cnt--; 
        if(DNA.charAt(i+k-1) === "C" || DNA.charAt(i+k-1) === "G") cnt++;
        if(cnt > max){
            max = cnt;
            start = i;
        }
    }
    console.log(DNA.slice(start,start+k));
}()