Submission #799539

#	Time	Username	Problem	Language	Result	Execution time	Memory
799539		PixelCat	Ancient Books (IOI17_books)	C++14	50 / 100	149 ms	35552 KiB

books

#include "books.h"
 
#ifdef NYAOWO
#include "grader.cpp"
#endif
 
#include <bits/stdc++.h>
#define For(i, a, b) for(int i = a; i <= b; i++)
#define Forr(i, a, b) for(int i = a; i >= b; i--)
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define sz(x) ((int)x.size())
#define eb emplace_back
#define int LL
using namespace std;
using i32 = int32_t;
using LL = long long;
using pii = pair<int, int>;
 
const int MAXN = 1'000'000;
const int INF = 1e18;
 
LL minimum_walk(vector<i32> p, i32 s) {
    assert(s >= 0);
    int n = sz(p);
 
    int ans = 0;
    vector<int> cid(n, -1);
    vector<pii> range;
    For(i, 0, n - 1) if(p[i] != i && cid[i] == -1) {
        int cur = i;
        int l = n + 1;
        int r = -1;
        do {
            l = min(l, cur);
            r = max(r, cur);
            ans += abs(p[cur] - cur);
            cur = p[cur];
            cid[cur] = sz(range);
        } while(cur != i);
        range.eb(l, r);
    }
    if(sz(range) == 0) return 0;
 
    int L = 0, R = n - 1;
    while(cid[L] == -1) L++;
    while(cid[R] == -1) R--;
    L = min(L, (int)s);
    R = max(R, (int)s);
    cerr << L << " " << R << "\n";
 
    vector<int> nxtl(n), nxtr(n);
    nxtl[0] = -INF;
    For(i, 1, n - 1) {
        if(cid[i - 1] != -1) nxtl[i] = i - 1;
        else nxtl[i] = nxtl[i - 1];
    }
    nxtr[n - 1] = INF;
    Forr(i, n - 2, 0) {
        if(cid[i + 1] != -1) nxtr[i] = i + 1;
        else nxtr[i] = nxtr[i + 1];
    }

    auto walk = [&](int l, int r, pii target) {
        int tl, tr;
        tie(tl, tr) = target;
        while(l > tl || r < tr) {
            if(l > tl) {
                l--;
                if(cid[l] != -1) {
                    tl = min(tl, range[cid[l]].F);
                    tr = max(tr, range[cid[l]].S);
                }
            } else {
                r++;
                if(cid[r] != -1) {
                    tl = min(tl, range[cid[r]].F);
                    tr = max(tr, range[cid[r]].S);
                }
            }
        }
        return pii(l, r);
    };
 
    int l = s, r = s;
    if(cid[s] != -1) {
        tie(l, r) = walk(l, r, range[cid[s]]);
    }
    while(l > L || r < R) {
        int l2, r2;

        int cl = 0;
        l2 = l; r2 = r;
        if(l2 == L) cl = INF;
        while(r2 == r && l2 != L) {
            cl += (l2 - nxtl[l2]) * 2;
            l2 = nxtl[l2];
            tie(l2, r2) = walk(l2, r2, range[cid[r2]]);
        }

        int cr = 0;
        l2 = l; r2 = r;
        if(r2 == R) cr = INF;
        while(l2 == l && r2 != R) {
            cr += (nxtr[r2] - r2) * 2;
            r2 = nxtr[r2];
            tie(l2, r2) = walk(l2, r2, range[cid[r2]]);
        }

        ans += min(cl, cr);
        tie(l, r) = walk(l, r, pii(l2, r2));
    }
    return ans;
}

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