Submission #134399

#	Time	Username	Problem	Language	Result	Execution time	Memory
134399		evpipis	Ancient Books (IOI17_books)	C++11	100 / 100	275 ms	24440 KiB

books

//#define TEST

#ifndef TEST
#include "books.h"
#endif
#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
typedef long long ll;
typedef pair<int, int> ii;

const int len = 1e6+6;
int n, per[len], dis[len], lef[len], rig[len];

int query(int st, int en){
    dis[st] = 0;
    int l = st, r = st, mn = lef[st], mx = rig[st], cnt = 0;
    while (0 < l || r < n-1){
        //printf("cnt = %d\n", cnt);
        while (mn < l || r < mx){
            if (mn < l){
                l--;
                dis[l] = cnt;
                mn = min(mn, lef[l]);
                mx = max(mx, rig[l]);
            }
            if (r < mx){
                r++;
                dis[r] = cnt;
                mn = min(mn, lef[r]);
                mx = max(mx, rig[r]);
            }

            //printf("l = %d, r = %d, mn = %d, mx = %d\n", l, r, mn, mx);
        }

        if (l > 0)
            mn = min(mn, lef[l-1]), mx = max(mx, rig[l-1]);
        if (r < n-1)
            mn = min(mn, lef[r+1]), mx = max(mx, rig[r+1]);
        cnt++;
    }

    //printf("dis starting from %d:\n", st);
    //for (int i = 0; i < n; i++)
      //  printf("i = %d, dis = %d\n", i, dis[i]);

    return dis[en];
}

ll minimum_walk(vector<int> P, int s){
    n = P.size();
    for (int i = 0; i < n; i++)
        per[i] = P[i];

    for (int i = 0; i < n; i++)
        lef[i] = -1;

    for (int i = 0; i < n; i++){
        if (lef[i] == -1){
            int cur = per[i], mn = i, mx = i;
            while (cur != i){
                mn = min(mn, cur);
                mx = max(mx, cur);
                cur = per[cur];
            }

            lef[i] = mn, rig[i] = mx;
            cur = per[i];
            while (cur != i){
                lef[cur] = mn, rig[cur] = mx;
                cur = per[cur];
            }
        }

        //printf("i = %d, mn = %d, mx = %d\n", i, lef[i], rig[i]);
    }

    ll ans = 0;
    for (int i = 0; i < n; i++)
        ans += abs(per[i]-i);

    int a = 0, b = n-1;
    while (a < s && per[a] == a)
        a++;
    while (b > s && per[b] == b)
        b--;

    ans += 2*query(s, a) + 2*query(b, s);

    return ans;
}

#ifdef TEST
int main() {
	int n, s, temp;
	assert(2 == scanf("%d %d", &n, &s));

	vector<int> p;
	for(int i = 0; i < n; i++){
		scanf("%d", &temp);
		p.pb(temp);
	}

	long long res = minimum_walk(p, s);

	printf("%lld\n", res);
	return 0;
}
#endif

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