重铸华农荣光 我辈义不容辞

the seventh day-interval merge

断更六天，倍感惭愧

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

typedef pair<int,int> PII;

void merge(vector<PII> &segs){
    vector<PII> res;
    sort(segs.begin(),segs.end());

    int st=-2e9,ed=-2e9;
    for(auto seg:segs){
        if(ed<seg.first){
            if(st!=-2e9) res.push_back({st,ed});
            st=seg.first,ed=seg.second;
        }
        else ed=max(ed,seg.second);
    }
    if(st!=-2e9) res.push_back({st,ed});

    segs=res;
}

int main()
{
    int n;
    cin>>n;

    vector<PII> segs;
    for(int i=0;i<n;i++){
        int l,r;
        cin>>l>>r;
        segs.push_back({l,r});
    }

    merge(segs);

    cout<<segs.size();

    return 0;
}