제출 #694651

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
694651		sharaelong	고대 책들 (IOI17_books)	C++17	100 / 100	171 ms	33960 KiB

books

#include "books.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;

const int MAX_N = 1e6 + 1;
const ll INF = 4e18;

int par[MAX_N];
int find(int x) {
    return par[x] = (x == par[x] ? x : find(par[x]));
}

bool visited[MAX_N];
int cycle_num[MAX_N];
int l[MAX_N], r[MAX_N];
int up[MAX_N];
int ldist[MAX_N], rdist[MAX_N], dist[MAX_N]; // minimum distance of moving cycle-component to its parent cycle-component
int recent[MAX_N];

ll minimum_walk(vector<int> p, int s) {
    int n = p.size();
    ll jump_len = 0;
    for (int i=0; i<n; ++i) jump_len += abs(i-p[i]);
    if (jump_len == 0) return 0;

    int cycle_cnt = 1;
    for (int i=0; i<n; ++i) {
        if (!cycle_num[i] && p[i] != i) {
            l[cycle_cnt] = i;
            for (int j=i; !cycle_num[j]; j=p[j]) {
                cycle_num[j] = cycle_cnt;
                r[cycle_cnt] = max(r[cycle_cnt], j);
            }
            cycle_cnt++;
        }
    }
    iota(par, par+n, 0);
    
    vector<int> st;
    for (int i=0; i<n; ++i) {
        if (cycle_num[i] > 0) {
            int c = find(cycle_num[i]);
            if (l[c] == i) {
                st.push_back(c);
            } else {
                while (!st.empty() && l[st.back()] > l[c]) {
                    par[st.back()] = c;
                    r[c] = max(r[c], r[st.back()]);
                    st.pop_back();
                }
                if (r[c] == i) {
                    st.pop_back();
                    if (!st.empty()) up[c] = st.back();
                }
            }
        }
    }
    for (int i=1; i<cycle_cnt; ++i) up[i] = find(up[i]);

    ll ans = 0;
    int last_root = 0;
    bool is_start_in_root = false;
    int root_min = n, root_max = -1;
    for (int i=1; i<cycle_cnt; ++i) {
        if (find(i) == i) {
            if (last_root > 0) {
                if (r[last_root] > l[i]) continue;
                ans += (l[i]-r[last_root]) * 2;
            }
            last_root = i;
            if (l[i] <= s && s <= r[i]) is_start_in_root = true;
            root_min = min(root_min, l[i]);
            root_max = max(root_max, r[i]);
        }
    }
    if (!is_start_in_root && root_min <= s && s <= root_max) return jump_len + ans;

    for (int i=0; i<n; ++i) {
        if (cycle_num[i] > 0) {
            int c = find(cycle_num[i]);
            recent[c] = i;
            if (up[c] > 0 && l[c] == i) ldist[c] = i-recent[up[c]];
            if (r[c] == i) recent[up[c]] = max(recent[up[c]], i-ldist[c]);
        }
    }
    for (int i=n-1; i>=0; --i) {
        if (cycle_num[i] > 0) {
            int c = find(cycle_num[i]);
            recent[c] = i;
            if (up[c] > 0 && r[c] == i) rdist[c] = recent[up[c]]-i;
            if (l[c] == i) recent[up[c]] = min(recent[up[c]], rdist[c]+i);
        }
    }
    for (int i=1; i<cycle_cnt; ++i) dist[i] = min(ldist[i], rdist[i]);
    for (int i=1; i<cycle_cnt; ++i) {
        // cycle numbering is set by l[i] order
        // thus accumulation of dist in x-axis order is valid
        if (up[i] > 0) dist[i] += dist[up[i]];
    }

    ll ans2 = INF;
    for (int i=0; i<n; ++i) {
        if (cycle_num[i] > 0) {
            int c = find(cycle_num[i]);
            ans2 = min(ans2, (ll)dist[c] + abs(i-s));
        }
    }
    return jump_len + ans + ans2 * 2;
}

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