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
    while ((line = await readline())) {
        let arr = line.split("");//转数组
        let array = [];
        for (let i = 0; i < arr.length; i++) {
            if (!array.includes(arr[i])) { //判断是否含相同字符
                array.push(arr[i]);
            }
        }
        console.log(array.length)
    }
})();