题解 | 小红的合数寻找

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

void (async function () {
    // Write your code here
    let res = -1;
    function isComposition(num) {
        if (num <= 1) return false;

        for (let i = 2; i <= Math.sqrt(num); i++) {
            if (num % i === 0) {
                return true;
            }
        }
        return false;
    }
    while ((line = await readline())) {
        let tokens = line.split(" ");
        let a = parseInt(tokens[0]);

        if (a === 1) {
            console.log(-1);
            return false;
        }
        let _a =a
        while (a <= _a*2) {

            let isCompo = isComposition(a);
                // console.log(isCompo,a);
            
            if (isCompo) {
                res = a;
                console.log(res);
                return false;
            }
            a++
        }
        console.log(res);
    }
})();