题解 | #找出字符串中第一个只出现一次的字符#

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

void async function () {
    const str = await readline();
    const map = new Map();
    for(const c of str){
        map.set(c,(map.get(c)||0)+1);
    }
    for(const c of str){
        if(map.get(c) === 1) return console.log(c);
    }
    console.log(-1);
}()