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 s = "";
    while(line = await readline()){
        // let tokens = line.split(' ');
        // let a = parseInt(tokens[0]);
        // let b = parseInt(tokens[1]);
        // console.log(a + b);
        s += line;
    }
    const set = new Set();
    for(let i = 0; i < s.length; i++) {
        if (0 <= s.charCodeAt(i) <= 127) {
            set.add(s[i])
        }
    }
    // console.log(set)
    console.log(set.size)
}()