python/TangDou/LuoGuBook/P1803.cpp

#include <bits/stdc++.h>

using namespace std;
typedef long long LL;
const int N = 110;
const int M = 1000010;
int n, ans, finish;
struct node {
    int l, r;
} con[M];

//按右端点排序
bool cmp(const node &a, const node &b) {
    return a.r <= b.r;
}

int main() {
    cin >> n;
    //输入
    for (int i = 1; i <= n; i++) cin >> con[i].l >> con[i].r;
    //排序
    sort(con + 1, con + 1 + n, cmp);

    for (int i = 1; i <= n; i++)
        if (finish <= con[i].l) //如果finish小于遍历于的线段左端点，那么可用。这句话是核心
            ans++, finish = con[i].r; //迭代的过程

    cout << ans << endl;
    return 0;
}