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  tag = false
      for (let i = 0; i < line.length; i++){
        const char = line.charAt(i)
        if (!line.substring(0,i).includes(char)&& !line.substring(i+1).includes(char)){
            console.log(char)
            tag = true
            break
        }
      }
    if(!tag) console.log(-1)
    }
}()

第一个唯一的字符，也就是说这个字符之前的子字符串找不到它，之后的子字符串也找不到它