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 () {
    // Write your code here
    while(line = await readline()){
        let tokens = line.split('');
        const res = []
        for(let c of tokens){
            const index = res.findIndex(item=>item[0] === c)
            if(index != -1) res[index][1]++
            else res.push([c,1])
        }
        // 找出第一个出现且只出现一次的
        const index = res.findIndex(item=>item[1] === 1)
        console.log(index === -1 ? index : res[index][0])
    }
}()