13C-非递减序列

#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

struct node
{
    int Left, Right, Height;
    vector<int> Lower;
};

typedef long long int64;
int N, M;
int Seq[5000];
node Nodes[5000];
int64 Result;

int main()
{
    int I, J;
    scanf("%d", &N);
    for (I = 0; I < N; I++) scanf("%d", Seq + I);
    M = 0;
    for (I = 0; I < N; I++)
        if (M == 0 || Seq[I] > Nodes[M - 1].Height)
        {
            Nodes[M].Left = Nodes[M].Right = I;
            Nodes[M++].Height = Seq[I];
        }
        else
        {
            Nodes[M - 1].Right++;
            if (Seq[I] < Nodes[M - 1].Height)
            {
                Nodes[M - 1].Lower.push_back(Seq[I]);
                push_heap(Nodes[M - 1].Lower.begin(), Nodes[M - 1].Lower.end());
            }
            while (Nodes[M - 1].Lower.size() * 2 >= Nodes[M - 1].Right - Nodes[M - 1].Left + 1)
            {
                J = Nodes[M - 1].Lower[0];
                if (M > 1 && Nodes[M - 2].Height > J) J = Nodes[M - 2].Height;
                while (!Nodes[M - 1].Lower.empty() && Nodes[M - 1].Lower[0] >= J)
                {
                    pop_heap(Nodes[M - 1].Lower.begin(), Nodes[M - 1].Lower.end());
                    Nodes[M - 1].Lower.pop_back();
                }
                Nodes[M - 1].Height = J;
                if (M > 1 && Nodes[M - 2].Height == J)
                {
                    M--;
                    if (Nodes[M - 1].Lower.size() < Nodes[M].Lower.size()) Nodes[M - 1].Lower.swap(Nodes[M].Lower);
                    Nodes[M - 1].Lower.reserve(Nodes[M - 1].Lower.size() + Nodes[M].Lower.size());
                    while (!Nodes[M].Lower.empty())
                    {
                        Nodes[M - 1].Lower.push_back(Nodes[M].Lower.back());
                        push_heap(Nodes[M - 1].Lower.begin(), Nodes[M - 1].Lower.end());
                        Nodes[M].Lower.pop_back();
                    }
                    Nodes[M].Lower.clear();
                    Nodes[M - 1].Right = Nodes[M].Right;
                }
            }
        }
    Result = 0;
    for (I = 0; I < M; I++) for (J = Nodes[I].Left; J <= Nodes[I].Right; J++)
        if (Seq[J] < Nodes[I].Height) Result += Nodes[I].Height - Seq[J];
        else Result += Seq[J] - Nodes[I].Height;
    printf("%I64d\n", Result);
    return 0;
}