Submission #777739

#	Time	Username	Problem	Language	Result	Execution time	Memory
777739		1bin	Aliens (IOI16_aliens)	C++14	100 / 100	94 ms	7552 KiB

aliens

#include <bits/stdc++.h>
#include "aliens.h"
 
using namespace std;
 
#define all(v) v.begin(), v.end()
typedef long long ll;
const ll NMAX = 5e5 + 5;
ll n, x, y, bx = -1, dp[NMAX];
vector<pair<ll, ll>> tmp, v;
ll m[NMAX], p[NMAX], sz, ii, cnt[NMAX];
 
int bad(int a, int b, int c){ return (p[b] - p[a]) * (m[b] - m[c]) >= (m[a] - m[b]) * (p[c] - p[b]);}
ll get(int i, ll x){return m[i] * x + p[i];}
 
void upd(ll mm, ll pp, int c){
    m[sz] = mm;
    p[sz] = pp;
    cnt[sz] = c;
    while(sz > 1 && bad(sz - 2, sz - 1, sz)){
        m[sz - 1] = m[sz];
        p[sz - 1] = p[sz];
        cnt[sz - 1] = cnt[sz];
        if(--sz == ii) ii--;
    }
    sz++;
    return;
}
 
ll f(ll x){
    while(ii + 1 < sz && get(ii, x) > get(ii + 1, x)) ii++;
    return get(ii, x);
}
 
pair<ll, ll> go(ll cost){
    sz = ii = 0;
    auto&[x, y] = v[0];
    upd(-2 * x, x * x, 0);
    for(int i = 1; i <= n; i++){
        auto&[x, y] = v[i - 1];
        pair<ll,ll> p = {f(y + 1) + (y + 1) * (y + 1) + cost, cnt[ii] + 1};
        if(i < n){
            ll xx = v[i].first;
            ll dy = max(y + 1LL - xx, 0LL);
            upd(-2 * xx, xx * xx - dy * dy + p.first, p.second);
        }
        else return p; 
    }
    return {-1, -1};
}
 
ll take_photos(int n_, int m, int k, vector<int> Y, vector<int> X) {
    n = n_;
    for(int i = 0; i < n; i++){
        y = Y[i]; x = X[i];
        if(x > y) swap(x, y);
        tmp.emplace_back(x, y);
    }
    sort(all(tmp));
    for(auto& [x, y] : tmp){
        if(v.size() && v.back().first == x) v.pop_back();
        if(v.empty() || v.back().second < y) v.emplace_back(x, y);
        bx = x;        
    }
    n = v.size();
    ll l = 0, r = 1LL * m * m, mid, ans = -1e18;
    while(l < r){
        mid = (l + r) / 2;
        auto p = go(mid);
        ans = max(ans, p.first - k * mid);
        if(p.second <= k) r = mid;
        else l = mid + 1;
    }
    return ans;
}
 
 
/*
int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int n, m, k;
    cin >> n >> m >> k;
    vector<int> X(n), Y(n);
    for(int& x : X) cin >> x;
    for(int& y : Y) cin >> y;
    cout << take_photos(n, m, k, X, Y);
    return 0;
}
*/

Compilation message (stderr)

aliens.cpp: In function 'std::pair<long long int, long long int> go(ll)':
aliens.cpp:37:10: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   37 |     auto&[x, y] = v[0];
      |          ^
aliens.cpp:40:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   40 |         auto&[x, y] = v[i - 1];
      |              ^
aliens.cpp: In function 'll take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:60:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   60 |     for(auto& [x, y] : tmp){
      |               ^

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 40 / 40