Submission #603137

#	Time	Username	Problem	Language	Result	Execution time	Memory
603137		wiwiho	Shortcut (IOI16_shortcut)	C++14	93 / 100	2084 ms	48372 KiB

shortcut

#include "shortcut.h"
 
#include <bits/stdc++.h>
#include <bits/extc++.h>
 
#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define ef(a) emplace_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define tomax(a, b) ((a) = max((a), (b)))
#define tomin(a, b) ((a) = min((a), (b)))
#define topos(a) ((a) = (((a) % MOD + MOD) % MOD))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
    if(pvaspace) b << " "; pvaspace=true;\
    b << pva;\
}\
b << "\n";}
 
using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
 
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;
 
const ll MOD = 1000000007;
const ll MAX = 1LL << 60;
 
template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
    return o << '(' << p.F << ',' << p.S << ')';
}
 
ll ifloor(ll a, ll b){
    if(b < 0) a *= -1, b *= -1;
    if(a < 0) return (a - b + 1) / b;
    else return a / b;
}
 
ll iceil(ll a, ll b){
    if(b < 0) a *= -1, b *= -1;
    if(a > 0) return (a + b - 1) / b;
    else return a / b;
}
 
int n;
vector<ll> p, d, s;
ll c;
vector<ll> discr;
vector<ll> tmp;
vector<ll> pos;

int lowbit(int x){
    return x & -x;
}

struct BIT{
    vector<pll> bit;
    void init(){
        bit.resize(n + 1, mp(MAX, -MAX)); // mn mx
    }
    void reset(){
        fill(iter(bit), mp(MAX, -MAX));
    }
    void modify(int x, pll v){
        x = n - x;
        for(; x < bit.size(); x += lowbit(x)){
            bit[x].F = min(bit[x].F, v.F);
            bit[x].S = max(bit[x].S, v.S);
        }
    }
    pll query(int x){
        x = n - x;
        pll ans = mp(MAX, -MAX);
        for(; x > 0; x -= lowbit(x)){
            ans.F = min(ans.F, bit[x].F);
            ans.S = max(ans.S, bit[x].S);
        }
        return ans;
    }
};

BIT bit;
 
struct event{
    ll x, y1, y2, ty;
    bool operator<(event b){
        return x < b.x;
    }
};
 
bool check(ll t){
    //cerr << "check " << t << "\n";
 
    //cerr << "tmp ";
    //printv(tmp, cerr);
 
    bit.reset();
 
    vector<event> ev;
 
    for(int a = n - 1; a >= 0; a--){
        ll X = t - d[a] - c;
        //cerr << "OAO " << a << "\n";;
        int id = upper_bound(iter(discr), t - d[a] + p[a]) - discr.begin();
        //cerr << "test " << a << " " << id << " " << t - d[a] + p[a] << "\n";
        if(id < n){
            pll owo = bit.query(id);
            ll mny = -X + owo.S;
            ll mxy = X + owo.F;
            if(mny > mxy) return false;
            mny *= 2;
            mxy *= 2;
            ll midx = p[a] * 2;
            ll midy = (mny + mxy) / 2;
            ll r = mxy - midy;
            ll mnx = midx - r;
            ll mxx = midx + r;
            //cerr << "rect " << midx << " " << midy << " " << r << "\n";
            
            ll x1 = mnx - midy;
            ll x2 = mxx - midy;
            ll y1 = mnx + midy;
            ll y2 = mxx + midy;
 
            ev.eb(event({x1, y1, y2, 0}));
            ev.eb(event({x2 + 1, y1, y2, 1}));
        }
        bit.modify(pos[a], mp(-d[a] + p[a], d[a] + p[a]));
    }
    //cerr << "ok\n";
 
    ll y1 = -MAX, y2 = MAX;
    ll x1 = -MAX, x2 = MAX;
    lsort(ev);
    int sz = ev.size();
    int cnt = 0;
    
    //cerr << "ok2 " << sz << "\n";
    for(int i = 0; i < sz; ){
        ll x = ev[i].x;
        int tc = 0;
        bool ed = false;
        for(; i < sz && ev[i].x == x; i++){
            //cerr << "do " << i << "\n";
            if(ev[i].ty == 1){
                x2 = x - 1;
                ed = true;
                break;
            }
            y1 = max(y1, ev[i].y1);
            y2 = min(y2, ev[i].y2);
            x1 = x;
            tc++;
        }
        if(y1 > y2 || ed) break;
        cnt += tc;
    }
    //cerr << "range " << x1 << " " << x2 << " " << y1 << " " << y2 << "\n";
 
    if(y1 > y2 || cnt != sz / 2) return false;
 
    for(int i = 0; i < n; i++){
        ll x = p[i] * 2;
        ll mny = max(y1 - x, x - x2);
        ll mxy = min(y2 - x, x - x1);
        //cerr << "owo " << i << " " << x << " " << mny << " " << mxy << "\n";
        auto it = lower_bound(iter(p), iceil(mny, 2));
        if(it != p.end() && *it * 2 <= mxy) return true;
    }
    return false;
}
 
ll find_shortcut(int _n, vector<int> len, vector<int> _d, int _c){
    n = _n;
    c = _c;
    
    p.resize(n);
    s.resize(n);
    d.resize(n);
    for(int i = 0; i < n; i++) d[i] = _d[i];
    for(int i = 0; i < n - 1; i++){
        p[i + 1] = p[i] + len[i];
    }
    for(int i = 0; i < n; i++){
        s[i] = p[i] + d[i];
    }
    bit.init();
 
    discr = s;
    tmp.resize(n);
    pos.resize(n);
    iota(iter(tmp), 0);
    sort(iter(tmp), [&](int x, int y){ return s[x] < s[y]; });
    for(int i = 0; i < n; i++){
        pos[tmp[i]] = i;
    }
    lsort(discr);
 
    ll l = 1, r = (ll)(1e9 + 5) * n + (ll)2e9 + 5;
    while(l < r){
        ll m = (l + r) / 2;
        if(check(m)) r = m;
        else l = m + 1;
    }
    //check(l);
 
    return l;
}

Compilation message (stderr)

shortcut.cpp: In member function 'void BIT::modify(int, pll)':
shortcut.cpp:86:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   86 |         for(; x < bit.size(); x += lowbit(x)){
      |               ~~^~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 8 / 8
• Subtask 4: 7 / 7
• Subtask 5: 33 / 33
• Subtask 6: 22 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3