题解 | #字符个数统计#

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 obj = {}
    while(line = await readline()){
        for(let i = 0; i < line.length; i++) {
            let char = line[i]
            let code = char.charCodeAt()
            if (code >= 0 && code <= 127) {
                if (obj[char]) {
                    obj[char]++
                } else {
                    obj[char] = 1
                }
            }
        }
    }
    console.log(Object.keys(obj).length)
}()