Submission #385168

#	Time	Username	Problem	Language	Result	Execution time	Memory
385168		ACmachine	Sparklers (JOI17_sparklers)	C++17	0 / 100	65 ms	492 KiB

sparklers

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using ordered_map = tree<T, U, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long ll;
typedef long double ld;

typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vi;
typedef vector<ll> vll;

#define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
#define FORD(i,j,k,in) for(int i=(j); i >=(k);i-=in)
#define REP(i,b) FOR(i,0,b,1)
#define REPD(i,b) FORD(i,b,0,1)
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define all(x) begin(x), end(x)
#define MANY_TESTS int tcase; cin >> tcase; while(tcase--)

const double EPS = 1e-9;
const int MOD = 1e9+7;
const ll INFF = 1e18;
const int INF = 1e9;
const ld PI = acos((ld)-1);
const vi dy = {1, 0, -1, 0, -1, 1, 1, -1};
const vi dx = {0, 1, 0, -1, -1, 1, -1, 1};

void DBG(){cout << "]" << endl;}
template<typename T, typename ...U> void DBG(const T& head, const U... args){ cout << head << "; "; DBG(args...); }
#define dbg(...) cout << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__);
#define chk() cout << "Check at line(" << __LINE__ << ") hit." << endl;

template<class T, unsigned int U>
ostream& operator<<(ostream& out, const array<T, U> &v){out << "[";  REP(i, U) out << v[i] << ", ";  out << "]"; return out;}
template <class T, class U>
ostream& operator<<(ostream& out, const pair<T, U> &par) {out << "[" << par.first << ";" << par.second << "]"; return out;}
template <class T>
ostream& operator<<(ostream& out, const set<T> &cont) { out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template <class T, class U>
ostream& operator<<(ostream& out, const map<T, U> &cont) {out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template<class T>
ostream& operator<<(ostream& out, const vector<T> &v){ out << "[";  REP(i, v.size()) out << v[i] << ", ";  out << "]"; return out;}

template<class T>
istream& operator>>(istream& in, vector<T> &v){ for(auto &x : v) in >> x; return in; }

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    int n, k; ll t;
    cin >> n >> k >> t;
    k--;
    vector<ll> x(n);
    cin >> x;
    REP(i, n) x[i] *= 2;
    auto check = [&](ll s, int mask) -> bool{
        int left = k - 1;
        int right = k + 1;
        ll curr_pos = x[k];
        ll curr_t = t * s;
        vector<ll> nx = x;
        REP(i, n - 1){
            if(mask&(1 << i)){
                if(left == -1)
                    return false;
                ll diff = abs(curr_pos - nx[left]) / 2;
                left--;
                if(diff > curr_t)
                    return false;
                curr_t -= diff;
                curr_t += t * s;
                curr_pos -= diff;
                REP(j, n){
                    if(nx[j] < curr_pos){
                        if(abs(nx[j] - curr_pos) > diff){
                            nx[j] += diff;
                        }
                        else{
                            nx[j] = curr_pos;
                        }
                    }
                    else{
                        if(abs(nx[j] - curr_pos) > diff){
                            nx[j] -= diff;
                        }
                        else{
                            nx[j] = curr_pos;
                        }
                    }
                }
            }
            else{
                if(right == n)
                    return false;
                ll diff = abs(curr_pos - nx[right]) / 2;
                right++;
                if(diff > curr_t)
                    return false;
                curr_t -= diff;
                curr_t += t * s;
                curr_pos += diff;
                REP(j, n){
                    if(nx[j] < curr_pos){
                        if(abs(nx[j] - curr_pos) > diff){
                            nx[j] += diff;
                        }
                        else{
                            nx[j] = curr_pos;
                        }
                    }
                    else{
                        if(abs(nx[j] - curr_pos) > diff){
                            nx[j] -= diff;
                        }
                        else{
                            nx[j] = curr_pos;
                        }
                    }
                }
            }
        }
        return true;
    };
    ll ans = INF;
    ll l = 1;
    ll r = (ll)1e9;
    while(l <= r){
        ll mid = (l + r) >> 1;
        bool can = false;
        REP(mask, (1 << (n - 1))){
            if(__builtin_popcount(mask) != k)
                continue;
            if(check(mid, mask)){
                can = true;
                break;
            }
        }
        if(can){
            ans = mid;
            r = mid - 1;
        }
        else{
            l = mid + 1;
        }
    }
    cout << ans / 2 + ans%2 <<"\n";
    return 0;
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50