题解 | #计算某字符出现次数#

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 index = 0;
    let str = "";
    let m = "";
    while ((line = await readline())) {
        if (index === 0) {
            str = line;
            index++;
        } else m = line;
    }
	// 如果m是大写，n就是小写，反之则反。
    m === m.toUpperCase() ? (n = m.toLowerCase()) : (n = m.toUpperCase());
    let arr = new Map();
    arr.set(m, 0);
    let num = 1;
    for (const i of str) {
        if (i === m || i === n ) {
            arr.set(m, num++);
        }
    }
    console.log(arr.get(m));
})();