【区间合并】AcWing803. 区间合并

AcWing803. 区间合并

题解

#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

typedef pair<int,int> PII;

vector<PII> segs;

void merge(vector<PII> &segs)
{
    vector<PII> res;
    int st = -2e9, ed = -2e9;
    
    sort(segs.begin(), segs.end());
    
    for(auto seg: segs)
     if(seg.first > ed)
     {
         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, l, r;
    cin >> n;
    for(int i = 0; i < n; ++i) cin >> l >> r, segs.push_back({l,r});
    
    merge(segs);
    
    cout << segs.size() << endl;
    return 0;
}