Submission #122970

#	Time	Username	Problem	Language	Result	Execution time	Memory
122970		someone_aa	Ancient Books (IOI17_books)	C++17	50 / 100	845 ms	31600 KiB

books

#include "books.h"
#include <bits/stdc++.h>
#define ll long long 
#define pb push_back
#define mp make_pair
using namespace std;
const int maxn = 1000100;
bool suffix[maxn];
int n, loc[maxn];

long long minimum_walk(std::vector<int> p, int s) {
	n = p.size();
	suffix[n] = true;
	for(int i=n-1;i>=0;i--) {
		suffix[i] = suffix[i+1] && (p[i] == i);
		loc[p[i]] = i;
	}

	ll result = 0LL;
	set<int>need;
	for(int i=0;i<n;i++) {
		if(suffix[i+1]) break;

		// if p[i] is in need

		if(need.find(p[i]) != need.end()) need.erase(p[i]);
		if(loc[i] > i) need.insert(i);

		/*cout<<"i: \n";
		for(int i:need) {
			cout<<i<<" ";
		} cout<<"\n";*/

		result += 2LL * max(1, int(need.size()));
	}

	return result;
}

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