Submission #1084682

#	Time	Username	Problem	Language	Result	Execution time	Memory
1084682		Tymond	Ancient Books (IOI17_books)	C++17	0 / 100	1 ms	344 KiB

books

#include <bits/stdc++.h>
#include "books.h"
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::steady_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

ll minimum_walk(vi p, int s){
    ll ans = 0LL;

    int n = sz(p);
    vi vis(n, 0);
    vi num(n, 0);
    vector<pii> range;
    int k = 0;
    int left = 1e9;
    int right = -1e9;
    for(int i = 0; i < n; i++){
        if(vis[i]){
            continue;
        }

        int akt = i;
        vis[i] = 1;
        num[i] = k;
        set<int> pos;
        pos.insert(akt);
        akt = p[akt];

        while(akt != i){
            vis[akt] = 1;
            num[akt] = k;
            pos.insert(akt);
            akt = p[akt];
        }

        range.pb({-1, -1});
        for(auto ele : pos){
            ans += ((ll)abs(ele - p[ele]));
            if(ele == s){
                range[k] = {s, s};
            }else if(ele > s){
                if(range[k].se == -1){
                    range[k].se = ele;
                }else{
                    range[k].se = min(range[k].se, ele);
                }
            }else if(ele < s){
                if(range[k].fi == -1){
                    range[k].fi = ele;
                }else{
                    range[k].fi = max(range[k].fi, ele);
                }
            }
        }

        if(range[k].fi == -1){
            right = max(right, range[k].se);
        }else if(range[k].se == -1){
            left = min(left, range[k].se);
        }
        k++;
    }

    ll res = -1;
    for(int i = n - 1; i >= s; i--){
        if(range[num[i]].se != i){
            continue;
        }

        if(res == -1){
            if(left == 1e9){
                res = (ll)ans + (ll)2 * (i - s);
            }else{
                res = (ll)ans + min(s - left, i - s) * 2 + max(s - left, i - s);
            }
        }else{
            if(left == 1e9){
                res = min(res, (ll)ans + (ll)2 * (i - s));
            }else{
                res = min(res, (ll)ans + min(s - left, i - s) * 2 + max(s - left, i - s));
            }
        }

        if(range[num[i]].fi == -1){
            break;
        }
        left = min(left, range[num[i]].fi);
    }

    return res;
}

/*int main(){
    cout << minimum_walk({0, 2, 3, 1}, 0) << '\n';
}*/

• Subtask 1: 0 / 12
• Subtask 2: 0 / 10
• Subtask 3: 0 / 28
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30