Submission #1073865

#	Time	Username	Problem	Language	Result	Execution time	Memory
1073865		ArthuroWich	Ancient Books (IOI17_books)	C++17	50 / 100	106 ms	29892 KiB

books

#include "books.h"
#include<bits/stdc++.h>
using namespace std;
int minl, maxr;
vector<int> pref, f1, f2, dp;
long long minimum_walk(vector<int> p, int s) {
    long long int ans = 0, n = p.size();
    pref.resize(n+1, 0);
    f1.resize(n, 0);
    f2.resize(n, 0);
    minl = INT_MAX;
    maxr = 0;
    for (int i = 0; i < n; i++) {
        ans += abs(i-p[i]);
    }
    vector<pair<int, int>> cycles;
    vector<int> vis(n, 0);
    for (int i = 0; i < n; i++) {
        if (p[i] == i || vis[i]) {
            continue;
        }
        int a = i, l = i, r = i;
        vis[i] = 1;
        a = p[i];
        vis[a] = 1;
        l = min(l, a);
        r = max(r, a);
        while(a != i) {
            a = p[a];
            vis[a] = 1;
            l = min(l, a);
            r = max(r, a);
        }
        minl = min(minl, l);
        maxr = max(maxr, r);
        cycles.push_back({min(l, r), max(l, r)});
    }
    for (auto [i, j] : cycles) {
        pref[i] += 1;
        pref[j] -= 1; 
    }
    for (int i = 1; i < n; i++) {
        pref[i] += pref[i-1];
    }
    f1[s] = 1;
    for (int i = 0; i < n; i++) {
        if (pref[i] > 0) {
            f1[i] = 1;
        }
        if (i > 0) {
            f1[i] |= f1[i-1];
        }
    }
    for (int i = n-1; i >= 0; i--) {
        if (pref[i] > 0) {
            f2[i] = 1;
        }
        if (i < n-1) {
            f2[i] |= f2[i+1];
        }
    }
    for (int i = n-1; i >= 0; i--) {
        if (f1[i] && f2[i] && pref[i] == 0) {
            ans += 2;
        }
    }
    return ans;
}

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