Submission #293018

#	Time	Username	Problem	Language	Result	Execution time	Memory
293018		amoo_safar	Ancient Books (IOI17_books)	C++17	12 / 100	32 ms	15224 KiB

books

#include "books.h"

#include <bits/stdc++.h>

#define pb push_back
#define F first
#define S second
#define all(x) x.begin(), x.end()

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;

const int N = 1e3 + 10;

int mk[N];
int L[N], R[N];
int mn[N][N], mx[N][N];
ll dp[N][N];

ll minimum_walk(vector<int> p, int s) {
	int n = p.size();
	ll ans = 0;
	ll near = n;
	for(int i = 0; i < n; i++){
		if(p[i] != i){
			ans += abs(p[i] - i);
			near = min(near, (ll) abs(s - i));
		} else mk[i] = 1;
	}
	int com = 0;
	vector<pii> seg;
	for(int i = 0; i < n; i++){
		if(mk[i]) continue;
		com ++;
		vector<int> vis;
		int nw = i;
		while(!mk[nw]){
			mk[nw] = 1;
			vis.pb(nw);
			nw = p[nw];
		}
		sort(all(vis));
		seg.pb({vis[0], vis.back()});
		for(auto x : vis) L[x] = vis[0];
		for(auto x : vis) R[x] = vis.back();
	}
	if(com == 0) return 0;
	
	for(int i = 0; i < n; i++) mn[i][i] = L[i];
	for(int i = 0; i < n; i++) mx[i][i] = R[i];
	for(int ln = 1; ln < n; ln ++){
		for(int i = 0; i + ln < n; i++){
			int j = i + ln;
			mn[i][j] = min(mn[i][j - 1], mn[i + 1][j]);
			mx[i][j] = max(mx[i][j - 1], mx[i + 1][j]);
		}
	}
	if(ans == 0) return 0;
	int st = 0, en = n - 1;
	while(p[st] == st) st ++;
	while(p[en] == en) en --;

	ll Inf = 1e18;

	for(int ln = n - 1; ln >= 0; ln--){
		for(int i = 0; i + ln < n; i++){
			int j = i + ln;
			if(i <= st && en <= j) dp[i][j] = 0;
			else if(mn[i][j] != i || mx[i][j] != j){
				dp[i][j] = dp[mn[i][j]][mx[i][j]];
			} else {
				dp[i][j] = 2 + min(i ? dp[i - 1][j] : Inf, j + 1 < n ? dp[i][j + 1] : Inf);
			}
		}
	}

	return ans + dp[s][s];
}

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