905. 区间选点 - AcWing题库

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;

struct Range
{
    int l,r;
    bool operator <(const Range&m)const
    {
        return r<m.r;
    }
}range[N];


int main()
{
    
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        cin>>range[i].l>>range[i].r;
    }
    
    sort(range,range+n);
    int l=0,r=-0x3f3f3f3f;
    int res=0;
    for(int i=0;i<n;i++)
    {
        if(r>=range[i].l)
        {
            continue;
        }
        else 
        {
            r=range[i].r;
            res++;
        }
        
    }
    cout<<res;
    
    
}

906. 区间分组 - AcWing题库

#include<bits/stdc++.h>
using namespace std;

const int N=1e5+10;
struct Range{
    
    
    int l,r;
    bool operator <(const Range &m)const
    {
        return l<m.l;
    }
}range[N];

int main()
{
    
    
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        cin>>range[i].l>>range[i].r;
        
    }
    
    sort(range,range+n);
    priority_queue<int ,vector<int>,greater<int>>q;
    q.push(range[0].r);
    int res=1;
    for(int i=1;i<n;i++)
    {   int x;
        x=q.top();
        if(range[i].l<=x)
        {
            res++;
            q.push(range[i].r);
        }
        else
        {
            q.pop();
            q.push(range[i].r);
        }
    }
    cout<<res;
    
    
    
}

907. 区间覆盖 - AcWing题库

#include<bits/stdc++.h>
using namespace std;


const int N=1e5+10;
struct Range
{
    int l,r;
    bool operator <(const Range&m)const 
    {
        return l<m.l;
    }
}range[N];

int main()
{
    int be,end;
    cin>>be>>end;
    int n;cin>>n;
    for(int i=0;i<n;i++)
    {
        cin>>range[i].l>>range[i].r;
    }
    sort(range,range+n);
    int res=0;
    int check=0;
    for(int i=0;i<n;i++)
    {   int j=i,r=-2e9;
        while(j<n&&range[j].l<=be)
        {
           
           r=max(r,range[j].r);
           //cout<<r<<endl;
           j++;
        }
       // cout<<endl;
        if(r==-2e9)
        {  
            check=0;
            break;
           
        }
        res++;
        //cout<<r<<endl;
        i=j-1;
        be=r;
        if(be>=end)
        {
            check=1;
            break;
        }
        
    }
    
    if(check) cout<<res;
    else cout<<-1;
}