#include<iostream>
#include<stack>
#include<string.h>
#include<cmath>
#include<iomanip>
#include<algorithm>
#include<climits>
#include<cstdio>
#include<vector>
#include<sstream>
#include<ctype.h>
#include<set>
#include<map>
#include<ctime>
#include<stdlib.h>
#include<queue>
#include<bitset>
#define ll long long
#define inf INT_MAX
using namespace std;
template<typename TTT>inline void mr(TTT& theNumberToRead)
{
	theNumberToRead = 0;
	bool prn = false;
	char c = getchar();
	while (!isdigit(c))
	{
		if (c == '-')prn = true;
		c = getchar();
	}
	while (isdigit(c))
		theNumberToRead = 10 * theNumberToRead + (c ^ 48), c = getchar();
	if (prn)
		theNumberToRead = -theNumberToRead;
}
template<typename TTT>inline TTT mrr()
{
	TTT theNumberToRead = 0;
	bool prn = false;
	char c = getchar();
	while (!isdigit(c))
	{
		if (c == '-')prn = true;
		c = getchar();
	}
	while (isdigit(c))
		theNumberToRead = 10 * theNumberToRead + (c ^ 48), c = getchar();
	return prn ? -theNumberToRead : theNumberToRead;
}
template<typename T>void my_write(T x)
{
	if (x)
		my_write(x / 10),
		putchar(x % 10 ^ 48);
}
template<typename T>void mw(T x, char mid)
{
	if (x)
	{
		if (x < 0)
			putchar('-'),
			x = -x;
		my_write(x);
	}
	else putchar(48);
	if (mid)
		putchar(mid);
}
// ******************************************华丽的分割线******************************************
// ******************************************华丽的分割线******************************************
// ******************************************华丽的分割线******************************************
// ******************************************华丽的分割线******************************************
// ******************************************华丽的分割线******************************************
typedef pair<int, int> P;
P a[500000];
int main()
{
	int n, m, k = 1, ans = 0;
	mr(n), mr(m);
	for (int i = 0; i < m; ++i)
		mr(a[i].first), mr(a[i].second);
	sort(a, a + m);
	while (k < n)
	{
		k = (upper_bound(a, a + m, P(k, INT_MAX)) - 1)->second, ++ans;
	}
	mw(ans, '\n');
	return 0;
}

• 数据太水了，其实这个解法是错的 (2959) Ioencgc 2023-07-25 10:52:15