题解 | #统计字符#

const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});
const letters = /[a-zA-Z]/g; // 匹配大小写英文字母
const num = /\d/g; // 匹配0-9数字
const empty = /\s/g; // 匹配空格
rl.on('line', function (line) {
// regx的match，匹配成功则返回对应匹配字符的数组集合，否则返回null，因此这里有一个兼容写法
    let l = (line.match(letters) || []).length;
    let n = (line.match(num) || []).length;
    let e = (line.match(empty) || []).length;
    console.log(l)
    console.log(e)
    console.log(n)
    console.log(line.length - l - n - e)
});