C++ :

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
using namespace std;
int a[1100],b[1100];

void qsort(int l,int r)
{
	int i,j,mid,p;
	i=l; j=r;
	mid=a[(l+r)/2];
	while (i<=j)
	{
		while (a[i]<mid) i++;
		while (a[j]>mid) j--;
		if (i<=j)
		{
			p=a[i]; a[i]=a[j]; a[j]=p;
			p=b[i]; b[i]=b[j]; b[j]=p;
			i++; j--;
			}
		}
	if (l<j) qsort(l,j);
	if (i<r) qsort(i,r);
} 

int main()
{
	int n,i,k,x,j,c[1010];
	cin>>n;
	for (i=1;i<=n;i++) 
	{
	  cin>>a[i]>>b[i];
	  a[i]=a[i]*10000+b[i];
	}
	qsort(1,n);
	k=1;
	c[1]=b[1];
	for (i=2;i<=n;i++)
	{
		x=0;
		for (j=1;j<=k;j++)
		if (c[j]<=b[i])
		{
			if (x==0) x=j;
			else
			if (c[j]>c[x]) x=j;
		}
		if (x==0) c[++k]=b[i];
		else c[x]=b[i];
		}
	cout<<k<<endl;
	return 0;
}

Pascal :

var
  l,w,p:array[1..1001] of longint;
  i,j,n,t:longint;
begin
  readln(n);
  for i := 1 to n do
    read(l[i],w[i]);
  for i:=1 to n-1 do
    for j:=i+1 to n do
      if (l[i]>l[j])or((l[i]=l[j])and(w[i]>w[j])) then
      begin
         t:=l[i];l[i]:=l[j];l[j]:=t;
         t:=w[i];w[i]:=w[j];w[j]:=t;
      end;
  i:=1;
  fillchar(p,sizeof(p),0);
  t:=0;
  for i:=1 to n do
    begin
      j:= 1;
      while p[j]>w[i] do inc(j);
      if j>t then inc(t);
      p[j]:=w[i];
    end;
  writeln(t);
end.

Python :

# coding=utf-8
# 零件分组（Stick）
def min_group(num_obj, obj_feature_pair):
    pair_list = []  # 组成对
    processed_list = []  # 被分组过的零件
    group = 0  # 组数
    for i in range(0, len(obj_feature_pair), 2):
        pair_list.append([obj_feature_pair[i], obj_feature_pair[i + 1]])
    pair_list.sort(key=lambda i: (i[0], i[1]))  # 按照长度-》重量排列零件
    while len(processed_list) != num_obj:
        min_f1 = -float('inf')
        min_f2 = -float('inf')
        start_flag = False  # 出现满足条件的零件标识
        for index, pair in enumerate(pair_list):
            if pair[0] >= min_f1 and pair[1] >= min_f2 and index not in processed_list:
                start_flag = True
                min_f1 = pair[0]
                min_f2 = pair[1]
                processed_list.append(index)
        if start_flag:
            group += 1
    return group


n = int(input())
li = list(map(int, input().split()))
print(min_group(n, li))