Submission #492859

#	Time	Username	Problem	Language	Result	Execution time	Memory
492859		balbit	Aliens (IOI16_aliens)	C++14	100 / 100	887 ms	24256 KiB

aliens

#include "aliens.h"
#include <bits/stdc++.h>
//#define int ll
using namespace std;
#define ll long long
#define y1 zck_is_king
#define pii pair<ll, ll>
#define ull unsigned ll
#define f first
#define s second
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define MN(a,b) a = min(a,(__typeof__(a))(b))
#define MX(a,b) a = max(a,(__typeof__(a))(b))
#define pb push_back
#define REP(i,n) for (int i = 0; i<n; ++i)
#define RREP(i,n) for (int i = n-1; i>=0; --i)
#define REP1(i,n) for (int i = 1; i<=n; ++i)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#ifdef BALBIT
#define IOS()
#define bug(...) fprintf(stderr,"#%d (%s) = ",__LINE__,#__VA_ARGS__),_do(__VA_ARGS__);
template<typename T> void _do(T &&x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T &&x, S &&...y){cerr<<x<<", ";_do(y...);}
#else
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'
#define bug(...)
#endif

const int iinf = 1e9+10;
const ll inf = 1ll<<60;
const ll mod = 1e9+7 ;


void GG(){cout<<"0\n"; exit(0);}

ll mpow(ll a, ll n, ll mo = mod){ // a^n % mod
    ll re=1;
    while (n>0){
        if (n&1) re = re*a %mo;
        a = a*a %mo;
        n>>=1;
    }
    return re;
}

ll inv (ll b, ll mo = mod){
    if (b==1) return b;
    return (mo-mo/b) * inv(mo%b,mo) % mo;
}

const int MM = 1e6+5;
const int NN = 1e5+5;
ll reach[MM]; // where does this point reach
ll over[NN]; // overcount for this index

ll dp[NN], take[NN];
ll at[NN], to[NN];

inline ll SQ(ll x) {return x*x;}

bool QTYPE = 0;
struct Line{
    mutable ll m, b, p, id;
    bool operator < (const Line &o) const {
        if (QTYPE) return p < o.p;
        return m < o.m;
    }
};

struct LineContainer : multiset<Line> {
    ll div(ll A, ll B) {
        return A/B - ((A%B) && ((A^B)<0));
    }
    bool isect (iterator x, iterator y) {
        if (y == end()) {
            x->p = inf; return false;
        }
        if (x->m == y->m) {
            x->p = x->b > y->b? inf : -inf;
        }else{
            x->p = div(x->b - y->b, y->m - x->m);
        }
        return x->p >= y->p;
    }

    void add(ll m, ll b, int id) {
        m=-m; b=-b;
        auto z = insert({m,b,0,id}), y = z++, x = y;
        while (isect(y,z)) z = erase(z);
        if (x!=begin() && isect(--x, y)) {
            isect(x, y = erase(y));
        }
        while ((y=x)!=begin() && (--x)->p >= y->p) {
            isect(x, erase(y));
        }
    }

    pii query(ll x) {

        QTYPE = 1;
        auto it = lower_bound({0,0,x,-1});
        ll ret = it->m * x + it->b;
        QTYPE = 0;
        return {-ret, it->id};
    }
};

pii brute(int n,ll pen) { // pen is (positive) penalty for each thing chosen
    LineContainer CV;
    REP(i,n+1) {
        if (i!=n && at[i] > to[i+1]) {
            over[i] = SQ(at[i] - to[i+1]);
        }
        if (i) {
            pii yo = CV.query(at[i]);
            dp[i] = yo.f + pen + SQ(at[i]);
            take[i] = take[yo.s]+1;
            bug(i, dp[i], take[i]);
        }
        CV.add(-2 * to[i+1], SQ(to[i+1]) - over[i] + dp[i], i);
    }
    return pii{dp[n], take[n]};
}



long long take_photos(int n, int m, int k, std::vector<int> ROW, std::vector<int> COL) {

    ll re = 0;
    memset(reach, 0x3f, sizeof reach);
    REP(i,n) {
        int a = ROW[i], b = COL[i];
        if (a > b) swap(a,b);
        MN(reach[b], a);
    }
    int nowdep = (0x3f3f3f3f)-1;
    vector<pii> use;
    for (int i = m-1; i>=0; --i) {
        if (reach[i] < nowdep) {
            nowdep = reach[i];
            use.emplace_back(i, reach[i]);
            bug(i, reach[i]);
        }
    }
    reverse(ALL(use));
    bug (SZ(use));
    at[0] = to[0] = -1;
    REP(i, SZ(use)){
        at[i+1] = use[i].f;
        to[i+1] = use[i].s-1;
    }

    {

        ll l = 0, r = 1e13;
        while (l!=r) {
            ll mid = (l+r)/2;
            pii hi = brute(SZ(use), mid);
            if (hi.s > k) {
                // taking too many! penalize!!!
                l = mid+1;
            }else{
                r = mid;
            }
        }

        bug(l);
        pii go = brute(SZ(use), l);
        ll re = (go.s) * -l - (k-go.s)*l + go.f;

        bug(re, go.f, go.s);
        return re;
    }



}


//signed main(){
//    ll r = take_photos(5, 7, 1, vector<int>{0, 4, 4, 4, 4}, vector<int>{3, 4, 6, 5, 6});
//    cout<<r<<endl;
//}
//




//signed main(){
//
//}

Compilation message (stderr)

aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:131:8: warning: unused variable 're' [-Wunused-variable]
  131 |     ll re = 0;
      |        ^~

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