题解 | 活动安排

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void (async function () {
    const n = parseInt(await readline());
    const activities = [];
    for (let i = 0; i < n; i++) {
        const [a, b] = (await readline()).split(" ").map(Number);
        activities.push({ start: a, end: b });
    }
    activities.sort((a, b) => a.end - b.end);
    let count = 0;
    let lastEnd = -1;
    for (const activity of activities) {
        if (activity.start >= lastEnd) {
            count++;
            lastEnd = activity.end;
        }
    }
    console.log(count);
})();