Submission #321758

#	Time	Username	Problem	Language	Result	Execution time	Memory
321758		alextodoran	3D Histogram (COCI20_histogram)	C++17	0 / 110	170 ms	270092 KiB

histogram

/**
 ____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|

**/

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N_MAX = 200002;
const int L_MAX = 1000002;

int n;

int a[N_MAX], b[N_MAX];

vector <pair <int, int> > vp;

bool active[N_MAX];

int root[N_MAX];

deque <int> stL[N_MAX], stR[N_MAX];

int L[N_MAX], R[N_MAX];

int findRoot (int u)
{
    if(root[u] == u)
        return u;
    return root[u] = findRoot(root[u]);
}

void mergeDeques (deque <int>* to, deque <int>* from)
{
    if((int)to->size() > (int)from->size())
    {
        while(from->empty() == false)
        {
            to->push_back(from->front());
            from->pop_front();
        }
    }
    else
    {
        while(to->empty() == false)
        {
            from->push_front(to->back());
            to->pop_back();
        }
        swap(to, from);
    }
}

vector <int> recalc;

ll maxArea;

void join (int u, int v)
{
    u = findRoot(u);
    v = findRoot(v);
    recalc.push_back(stL[v].front());
    while(stL[u].empty() == false && a[stL[u].back()] >= a[stL[v].front()])
    {
        L[stL[v].front()]++;
        stL[u].pop_back();
    }
    recalc.push_back(stR[u].front());
    while(stR[v].empty() == false && a[stR[v].back()] >= a[stR[u].front()])
    {
        R[stR[u].front()]++;
        stR[v].pop_back();
    }
    mergeDeques(&stL[v], &stL[u]);
    mergeDeques(&stR[v], &stR[u]);
    root[u] = v;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    for(int i = 1; i <= n; i++)
        cin >> a[i] >> b[i];
    for(int i = 1; i <= n; i++)
        vp.push_back(make_pair(b[i], i));
    sort(vp.begin(), vp.end());
    reverse(vp.begin(), vp.end());
    for(int i = 1; i <= n; i++)
    {
        root[i] = i;
        active[i] = false;
        stL[i].push_back(i);
        stR[i].push_back(i);
        L[i] = R[i] = 0;
    }
    ll ans = 0;
    for(pair <int, int> p : vp)
    {
        int i = p.second;
        active[i] = true;
        if(i > 1 && active[i - 1] == true)
            join(i - 1, i);
        if(i < n && active[i + 1] == true)
            join(i, i + 1);
        recalc.push_back(i);
        for(int r : recalc)
            maxArea = max(maxArea, 1LL * (L[r] + R[r] + 1) * a[r]);
        recalc.clear();
        ans = max(ans, maxArea * b[i]);
    }
    cout << ans << "\n";
    return 0;
}

• Subtask 1: 0 / 20
• Subtask 2: 0 / 90