Submission #777015

#	Time	Username	Problem	Language	Result	Execution time	Memory
777015		1bin	Aliens (IOI16_aliens)	C++17	0 / 100	1 ms	340 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<int, int>> tmp, v;
ll m[NMAX], p[NMAX], sz, ii, cnt[NMAX];

int cross(int a, int b) { return 1.0 *(p[b] - p[a]) / (m[a] - m[b]); }
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){
    m[sz] = mm;
    p[sz] = pp;
    while(sz > 1 && bad(sz - 2, sz - 1, sz)){
        m[sz - 1] = sz;
        p[sz - 1] = 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);
}

int go(ll cost){
    sz = ii = 0;
    auto&[x, y] = v[0];
    upd(-2 * x, x * x);
    for(int i = 1; i <= n; i++){
        auto&[x, y] = v[i - 1];
        dp[i] = f(y + 1) + (y + 1) * (y + 1) + cost;
        cnt[i] = 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 + dp[i]);
        }
    }
    return cnt[n];
}

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(x == bx) 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;
    while(l < r){
        mid = (l + r) / 2;
        if(go(mid) <= k) r = mid;
        else l = mid + 1;
    }
    go(l);
	return dp[n] - l * k;
}


/*
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;
}
*/

• Subtask 1: 0 / 4
• Subtask 2: 0 / 12
• Subtask 3: 0 / 9
• Subtask 4: 0 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 40