[JSOI2007]建筑抢修

#include 
#include 
#define MAX 150000
#define ll long long

using namespace std;

struct building
{
    ll T1;
    ll T2;
}Building[MAX], Heap[MAX];

int cmp(const building & a, const building & b)
{
    if(a.T2 != b.T2) return a.T2 < b.T2;
    return a.T1 < b.T1;
}

int Heapcmp(const building & a, const building & b)
{
    return a.T1 < b.T1;
}

int main()
{
    int N, tot = 0;
    ll ans = 0;
    cin >> N;
    for(int i = 1; i <= N; ++i)
        cin >> Building[i].T1 >> Building[i].T2;
    sort(Building + 1, Building + N + 1, cmp);
    for(int i = 1; i <= N; ++i)
    {
        if(ans + Building[i].T1 <= Building[i].T2)
        {
            Heap[++tot] = Building[i];
            push_heap(Heap + 1, Heap + 1 + tot, Heapcmp);
            ans = ans + Building[i].T1;
        }
        else if(tot != 0)
        {
            building step = Heap[1];
            if(Building[i].T1 >= step.T1) continue;
            pop_heap(Heap + 1, Heap + 1 + tot, Heapcmp);
            Heap[tot] = Building[i];
            push_heap(Heap + 1, Heap + 1 + tot, Heapcmp);
            ans = ans + Building[i].T1 - step.T1;
        }
    }
    cout << tot;
    return 0;
}