Submission #916083

#	Time	Username	Problem	Language	Result	Execution time	Memory
916083		boris_mihov	Constellation 3 (JOI20_constellation3)	C++17	35 / 100	1554 ms	93268 KiB

constellation3

#include <algorithm>
#include <iostream>
#include <cassert>
#include <numeric>
#include <vector>
#include <stack>

typedef long long llong;
const int MAXLOG = 19;
const int MAXN = 400000 + 10;
const int INF  = 1e9;

int n, m;
int a[MAXN];
int h[MAXN];
int cntSegm;

struct Sparse
{
    int sparse[MAXLOG][MAXN];
    void build(int par[])
    {
        for (int i = 1 ; i <= cntSegm ; ++i)
        {
            sparse[0][i] = par[i];
        }

        for (int log = 1 ; (1 << log) <= cntSegm ; ++log)
        {
            for (int i = 1 ; i <= cntSegm ; ++i)
            {
                sparse[log][i] = sparse[log - 1][sparse[log - 1][i]];
            }
        }
    }

    int find(int x, int y)
    {
        for (int log = MAXLOG - 1 ; log >= 0 ; --log)
        {
            if (h[sparse[log][x]] < y)
            {
                x = sparse[log][x];
            }
        }

        return x;
    }
};

int x[MAXN];
int y[MAXN];
int c[MAXN];
int par[MAXN];
llong dp[MAXN];
llong sum[MAXN];
int leftSegm[MAXN];
int rightSegm[MAXN];
int leftBigger[MAXN];
std::vector <int> g[MAXN];
std::vector <int> stars[MAXN];
std::stack <int> st;
Sparse sparse;

llong getSum(int node, int to)
{
    if (node == to)
    {
        return sum[node] - dp[node];
    }

    return sum[node] - dp[node] + getSum(par[node], to);
}

void dfs(int node)
{
    for (const int &u : g[node])
    {
        dfs(u);
        sum[node] += dp[u];
    }

    llong res = sum[node];
    for (const int &idx : stars[node])
    {
        res = std::max(res, c[idx] + getSum(par[leftSegm[x[idx]]], node));
    }

    dp[node] = res;
}

void solve()
{
    a[0] = INF;
    h[0] = INF;
    st.push(0);
    for (int i = 1 ; i <= n ; ++i)
    {
        while (a[st.top()] < a[i])
        {
            st.pop();
        }

        leftBigger[i] = st.top();
        st.push(i);
    }

    while (st.size())
    {
        st.pop();
    }

    for (int i = 1 ; i <= n ; ++i)
    {
        bool wasThere = false;
        if (a[leftBigger[i]] == a[i]) 
        {
            wasThere = true;
            leftSegm[i] = rightSegm[leftBigger[i]];
        } else 
        {
            leftSegm[i] = ++cntSegm;
        }

        rightSegm[i] = ++cntSegm;
        h[leftSegm[i]] = a[i];
        h[rightSegm[i]] = a[i];

        while (st.size() && a[st.top()] < a[i])
        {
            if (!wasThere && (par[leftSegm[st.top()]] == 0 || h[par[leftSegm[st.top()]]] > a[i]))
            {
                par[rightSegm[st.top()]] = leftSegm[i];
                par[leftSegm[st.top()]] = leftSegm[i];
            }
            
            st.pop();
        }

        if (st.size())
        {
            if (a[st.top()] > a[i]) 
            {
                par[leftSegm[i]] = rightSegm[st.top()];
                par[rightSegm[i]] = rightSegm[st.top()];
            } else 
            {
                par[leftSegm[i]] = par[rightSegm[st.top()]];
                par[rightSegm[i]] = par[rightSegm[st.top()]];
            }
        }
        
        st.push(i);
    }


    for (int i = 1 ; i <= cntSegm ; ++i)
    {
        g[par[i]].push_back(i);
    }

    sparse.build(par);
    llong sumStars = 0;
    for (int i = 1 ; i <= m ; ++i)
    {
        stars[par[sparse.find(leftSegm[x[i]], y[i])]].push_back(i);
        sumStars += c[i];
    }

    dfs(0);
    std::cout << sumStars - dp[0] << '\n';
}

void input()
{
    std::cin >> n;
    for (int i = 1 ; i <= n ; ++i)
    {
        std::cin >> a[i];
    }

    std::cin >> m;
    for (int i = 1 ; i <= m ; ++i)
    {
        std::cin >> x[i] >> y[i] >> c[i];
    }
}

void fastIOI()
{
    std::ios_base :: sync_with_stdio(0);
    std::cout.tie(nullptr);
    std::cin.tie(nullptr);
}

int main()
{
    fastIOI();
    input();
    solve();

    return 0;
}

• Subtask 1: 14 / 14
• Subtask 2: 21 / 21
• Subtask 3: 0 / 65