Submission #353168

#	Time	Username	Problem	Language	Result	Execution time	Memory
353168		dolphingarlic	Ancient Books (IOI17_books)	C++14	0 / 100	43 ms	7084 KiB

books

#include "books.h"

#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

int crit_l, crit_r, cmp_cnt;
int cmp[1000000], cmp_l[1000000], cmp_r[1000000];
map<pair<int, int>, ll> dp;

void extend(int &l, int &r) {
    int ext_l = min(cmp_l[cmp[l]], cmp_l[cmp[r]]);
    int ext_r = max(cmp_r[cmp[l]], cmp_r[cmp[r]]);
    while (l != ext_l || r != ext_r) {
        while (l != ext_l) {
            l--;
            ext_l = min(ext_l, cmp_l[cmp[l]]);
            ext_r = max(ext_r, cmp_r[cmp[l]]);
        }
        while (r != ext_r) {
            r++;
            ext_l = min(ext_l, cmp_l[cmp[r]]);
            ext_r = max(ext_r, cmp_r[cmp[r]]);
        }
    }
}

ll compute(int l, int r) {
    if (dp.count({l, r})) return dp[{l, r}];
    ll ans = LLONG_MAX;
    if (l != crit_l) {
        int nl = l - 1, nr = r;
        extend(nl, nr);
        ans = min(ans, compute(nl, nr) + 2);
    }
    if (r != crit_r) {
        int nl = l, nr = r + 1;
        extend(nl, nr);
        ans = min(ans, compute(nl, nr) + 2);
    }
    return dp[{l, r}] = ans;
}

ll minimum_walk(vector<int> p, int s) {
    fill(cmp, cmp + p.size(), -1);
    cmp_cnt = 0, crit_l = s, crit_r = s;
    ll intra = 0;
    for (int i : p) {
        intra += abs(p[i] - i);
        if (cmp[i] == -1) {
            int curr = i, sz = 0;
            cmp_l[cmp_cnt] = cmp_r[cmp_cnt] = i;
            do {
                cmp[curr] = cmp_cnt;
                cmp_l[cmp_cnt] = min(cmp_l[cmp_cnt], curr);
                cmp_r[cmp_cnt] = max(cmp_r[cmp_cnt], curr);
                curr = p[curr];
                sz++;
            } while (curr != i);
            if (sz != 1) {
                crit_l = min(crit_l, cmp_l[cmp_cnt]);
                crit_r = max(crit_r, cmp_r[cmp_cnt]);
            }
            cmp_cnt++;
        }
    }
    dp[{crit_l, crit_r}] = 0;
    return intra + compute(s, s);
}

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