区间和并

区间和并

// 将所有存在交集的区间合并
void merge(vector<PII> &segs)
{
    vector<PII> res;

    //按照先左边，后右边进行排序
    sort(segs.begin(), segs.end());

    int st = -2e9, ed = -2e9;//负无穷
    
    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;
}