Submission #1140863

#	Time	Username	Problem	Language	Result	Execution time	Memory
1140863		steveonalex	Ancient Books (IOI17_books)	C++20	70 / 100	2093 ms	32252 KiB

books

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ull mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
    double cur = rngesus(0, MASK(60) - 1);
    cur /= MASK(60) - 1;
    return l + cur * (r - l);
}
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

#include "books.h"

const int INF = 1e9 + 69;
struct SegmentTree{
    int n;
    vector<int> a;

    SegmentTree(int _n){
        n = _n;
        a.resize(n * 2 + 2, -INF);
    }

    void update(int i, int v){
        i += n; if (!maximize(a[i], v)) return;
        while(i > 1){
            i >>= 1;
            a[i] = max(a[i * 2], a[i * 2 + 1]);
        }
    }

    int get(int l, int r){
        l += n; r += n + 1;
        int ans = -INF;
        while(l < r){
            if (l & 1) maximize(ans, a[l++]);
            if (r & 1) maximize(ans, a[--r]);
            l >>= 1; r >>= 1;
        }
        return ans;
    }
};

ll minimum_walk(vector<int> p, int s) {
    int n = p.size();
    for(int &i: p) i++;
    p.insert(p.begin(), 0);

    ll ans = 0;
    pair<int, int> min_range = {n, 1};
    for(int i = 1; i <= n; ++i){
        ans += abs(i - p[i]);
        if (i !=p[i]){
            minimize(min_range.first, i);
            maximize(min_range.second, i);
        }
    }

    vector<pair<int,int>> big_range(n+1, {-1, -1});
    for(int i = 1; i <= n; ++i){
        if (big_range[i].first != -1) continue;
        pair<int,int> mi = {i, i};
        int j = p[i];
        while(j != i){
            minimize(mi.first, j); maximize(mi.second, j);
            j = p[j];
        }

        do{
            big_range[j] = mi;
            j = p[j];
        } while(j != i);
    }

    for(int i = 1; i <= n; ++i){
        minimize(big_range[i].first, i);
        maximize(big_range[i].second, i);
    }

    SegmentTree mi(n), ma(n);
    for(int i = 1; i <= n; ++i) {
        mi.update(i, -big_range[i].first);
        ma.update(i, big_range[i].second);
    }

    map<pair<int, int>, ll> dp;
    s++;
    dp[make_pair(-s, s)] = 0;
    ll best = INF;
    while(dp.size()){
        auto u = *dp.begin();
        dp.erase(dp.begin());
        pair<int, int> range = u.first;
        ll cost = u.second;

        range.first *= -1;
        if (range.first <= min_range.first && range.second >= min_range.second) minimize(best, cost);
        pair<int,int> tmp = make_pair(-mi.get(range.first, range.second), ma.get(range.first, range.second));

        if (tmp == range){
            cost += 2;
            if (range.first > 1){
                pair<int,int> tmp = {range.first - 1, range.second};
                tmp.first *= -1;
                if (dp.count(tmp)) minimize(dp[tmp], cost);
                else dp[tmp] = cost;
            }
            if (range.second < n){
                pair<int,int> tmp = {range.first, range.second + 1};
                tmp.first *= -1;
                if (dp.count(tmp)) minimize(dp[tmp], cost);
                else dp[tmp] = cost;
            }
        }
        else{
            tmp.first *= -1;
            if (dp.count(tmp)) minimize(dp[tmp], cost);
            else dp[tmp] = cost;
        }
    }

    return ans + best;
}

// int main(void){
//     ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);

//     clock_t start = clock();

//     int n; cin >> n;
//     vector<int> p(n);
//     for(int i = 0; i<n; ++i) cin >> p[i];


//     int s; cin >> s;
//     cout << minimum_walk(p, s) << "\n";

//     cerr << "Time elapsed: " << clock() - start << " ms\n";
//     return 0;
// }

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