Submission #364618

#	Time	Username	Problem	Language	Result	Execution time	Memory
364618		rqi	Ancient Books (IOI17_books)	C++14	50 / 100	181 ms	22892 KiB

books

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

typedef vector<int> vi;
typedef long long ll;

#define sz(x) (int)(x).size()

long long minimum_walk(vi p, int s) {
	bool all_good = 1;
	for(int i = 0; i < sz(p); i++){
		if(p[i] != i) all_good = 0;
	}
	if(all_good) return 0;

	int n = sz(p);
	vi cover = vi(n, 0);
	vi dirover = vi(n, 0); //right = +1
	ll ans = 0;
	for(int i = 0; i < n; i++){
		cover[min(i, p[i])]++;
		cover[max(i, p[i])]--;
		dirover[i]++;
		dirover[p[i]]--;
		ans+=abs(p[i]-i);
	}

	//cout << ans << "\n";

	for(int i = 1; i < n; i++){
		cover[i]+=cover[i-1];
		dirover[i]+=dirover[i-1];
	}

	

	for(int i = 0; i < n; i++){
		ans+=abs(dirover[i]);
	}

	int L = 0;
	int R = n-2;
	for(int i = 0; i <= s-1; i++){
		if(p[i] == i){
			L = i+1;
		}
		else break;
	}
	for(int i = n-2; i >= s; i--){
		if(p[i+1] == i+1){
			R = i-1;
		}
		else break;
	}

	for(int i = L; i <= R; i++){
		if(cover[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