oj.uz

Submission #316369

# Submission time Handle Problem Language Result Execution time Memory
316369 2020-10-26T07:50:18 Z georgerapeanu 3D Histogram (COCI20_histogram) C++11
20 / 110
 1871 ms 40812 KB 
#include <bits/stdc++.h>

using namespace std;

const int NMAX = 2e5;

long long det(pair<int,int> a,pair<int,int> b,pair<int,int> c) {
    return 1LL * a.first * (b.second - c.second) + 1LL * b.first * (c.second - a.second) + 1LL * c.first * (a.second - b.second);
}

bool cmp(pair<int,int> a,pair<int,int> b) {
    return det(make_pair(0,0),a,b) > 0;
}

struct node_t {

    int lst_ind;
    vector<pair<long long,long long> > points;

    node_t operator + (const node_t &other)const {
        node_t ans;
       
        if(this->points.size() == 0){
            ans = *this;
            ans.lst_ind = this->points.size() - 1;
            return ans;
        }
        if(other.points.size() == 0){
            ans = other;
            ans.lst_ind = other.points.size() - 1;
            return ans;
        }

        int i = 0;
        int j = 0;

        while(i < (int)points.size() && j < (int)other.points.size()){
            pair<long long,long long> p;
            if(cmp(points[i],other.points[j]) == true){
                p = points[i++];
            }
            else{
                p = other.points[j++];
            }
            while((int)ans.points.size() > 2 && det(ans.points[(int)ans.points.size() - 2],ans.points[(int)ans.points.size() - 1],p) < 0){
                ans.points.pop_back();
            }
            ans.points.push_back(p);
        }
        while(i < (int)points.size()){
            pair<long long,long long> p;
            p = points[i++];
            while((int)ans.points.size() > 2 && det(ans.points[(int)ans.points.size() - 2],ans.points[(int)ans.points.size() - 1],p) < 0){
                ans.points.pop_back();
            }
            ans.points.push_back(p);
        }
        while(j < (int)other.points.size()){
            pair<long long,long long> p;
            p = other.points[j++];
            while((int)ans.points.size() > 2 && det(ans.points[(int)ans.points.size() - 2],ans.points[(int)ans.points.size() - 1],p) < 0){
                ans.points.pop_back();
            }
            ans.points.push_back(p);
        }

        ans.lst_ind = (int)ans.points.size() - 1;

        return ans;
    }

    long long query(pair<long long,long long> v) {
        while(lst_ind - 1 >= 0 && points[lst_ind].first * v.first + points[lst_ind].second * v.second <= points[lst_ind - 1].first * v.first + points[lst_ind - 1].second * v.second) {
            lst_ind--;
        }
        return points[lst_ind].first * v.first + points[lst_ind].second * v.second;
    }

    node_t() {
        lst_ind = 0;
        points = vector<pair<long long,long long> >();
    }

};

class SegmentTree {
    int n;
    vector<node_t> aint;

public:

    SegmentTree(int n,vector<pair<long long,long long> > v) {
        this->n = n;
        this->aint = vector<node_t>(2 * n + 5,node_t());
        for(int i = 1;i <= n;i++){
            aint[n + i].points = {v[i]};
        }
        for(int i = n;i;i--){
            aint[i] = aint[(i << 1)] + aint[(i << 1) | 1];
        }
    }

    long long query(int l,int r,pair<long long,long long> v) {
        long long ans = 0;
        l += n;
        r += n + 1;

        for(;l < r;l >>= 1,r >>= 1){
            if(l & 1){
                ans = max(ans,aint[l++].query(v));
            }
            if(r & 1){
                ans = max(ans,aint[--r].query(v));
            }
        }

        return ans;
    }

};

int n;
int a[NMAX + 5];
int b[NMAX + 5];

long long solve(int st,int dr) {
    if(st == dr) {
        return 1LL * a[st] * b[st];
    }

    int mid = (st + dr) / 2;

    long long ans = max(solve(st,mid),solve(mid + 1,dr));

    int mi_a = 1e9;
    int mi_b = 1e9;

    int i_a = mid;
    int i_b = mid;
    int i2_b = mid;

    vector<pair<long long,long long> > points = {};

    int mip_b = 1e9;

    for(int i = mid; i >= st; i--) {
        mip_b = min(mip_b,b[i]);
        points.push_back({1LL * mip_b,1LL * mip_b * (1 - i)});
    }
    points.push_back({0LL,0LL});
    reverse(points.begin(),points.end());

    SegmentTree aint(mid - st + 1,points);

    for(int i = mid + 1; i <= dr; i++) {
        mi_a = min(mi_a,a[i]);
        mi_b = min(mi_b,b[i]);
        while(i_a >= st && a[i_a] >= mi_a) {
            i_a--;
        }
        while(i_b >= st && b[i_b] > mi_b) {
            i_b--;
        }
        while(i2_b >= st && b[i2_b] >= mi_b) {
            i2_b--;
        }
        ans = max(ans,1LL * mi_a * mi_b * (i - max(i_a,i2_b)));
        if(i_a + 1 <= i_b) {
            ans = max(ans,aint.query(i_a + 1 - (st - 1),i_b - (st - 1),make_pair(1LL * mi_a * i,1LL * mi_a)));
        }
        ///[i_a + 1,i_b]
    }
    return ans;
}

const int LEN = 1 << 12;
char buff[LEN];
int ind = LEN - 1;

int i32(){
    int ans = 0;

    while(buff[ind] < '0' || buff[ind] > '9'){
        if(++ind >= LEN){
            ind = 0;
            fread(buff,1,LEN,stdin);
        }
    }
    
    while(!(buff[ind] < '0' || buff[ind] > '9')){
        ans = ans * 10 + buff[ind] - '0';
        if(++ind >= LEN){
            ind = 0;
            fread(buff,1,LEN,stdin);
        }
    }

    return ans;
}

int main() {

    n = i32();

    for(int i = 1; i <= n; i++) {
        a[i] = i32();
        b[i] = i32();
    }

    long long ans = 0;

    ans = max(ans,solve(1,n));
    ans = max(ans,solve(1,n));
    swap(a,b);
    ans = max(ans,solve(1,n));
    reverse(a + 1,a + 1 + n);
    reverse(b + 1,b + 1 + n);
    ans = max(ans,solve(1,n));
    swap(a,b);

    printf("%lld\n",ans);

    return 0;
}

Compilation message

histogram.cpp: In function 'int i32()':
histogram.cpp:186:18: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  186 |             fread(buff,1,LEN,stdin);
      |             ~~~~~^~~~~~~~~~~~~~~~~~
histogram.cpp:194:18: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  194 |             fread(buff,1,LEN,stdin);
      |             ~~~~~^~~~~~~~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 1996 KB Output is correct
2 Correct 10 ms 2140 KB Output is correct
3 Correct 10 ms 2124 KB Output is correct
4 Correct 10 ms 2124 KB Output is correct
5 Correct 9 ms 2112 KB Output is correct
6 Correct 11 ms 2152 KB Output is correct
7 Correct 15 ms 1996 KB Output is correct
8 Correct 11 ms 2124 KB Output is correct
9 Correct 10 ms 2124 KB Output is correct
10 Correct 9 ms 2132 KB Output is correct
11 Correct 2 ms 1868 KB Output is correct
12 Correct 14 ms 2140 KB Output is correct

Subtask #2
0 / 90.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 1996 KB Output is correct
2 Correct 10 ms 2140 KB Output is correct
3 Correct 10 ms 2124 KB Output is correct
4 Correct 10 ms 2124 KB Output is correct
5 Correct 9 ms 2112 KB Output is correct
6 Correct 11 ms 2152 KB Output is correct
7 Correct 15 ms 1996 KB Output is correct
8 Correct 11 ms 2124 KB Output is correct
9 Correct 10 ms 2124 KB Output is correct
10 Correct 9 ms 2132 KB Output is correct
11 Correct 2 ms 1868 KB Output is correct
12 Correct 14 ms 2140 KB Output is correct
13 Correct 1828 ms 39404 KB Output is correct
14 Correct 1584 ms 40784 KB Output is correct
15 Correct 1871 ms 40684 KB Output is correct
16 Correct 1801 ms 40736 KB Output is correct
17 Incorrect 1791 ms 40812 KB Output isn't correct
18 Halted 0 ms 0 KB -