Submission #984035

#	Time	Username	Problem	Language	Result	Execution time	Memory
984035		CSQ31	Ancient Books (IOI17_books)	C++17	50 / 100	107 ms	28244 KiB

books

#include "books.h"
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define sz(a) (int)(a.size())
#define all(a) a.begin(),a.end()
typedef long long int ll;
typedef pair<int,int> pii;
const int MAXN = 1e6+1;
int par[MAXN];
int mn[MAXN],mx[MAXN];

int find(int x){
	if(x==par[x])return x;
	return par[x] = find(par[x]);
}

void unite(int a,int b){
	a = find(a);
	b = find(b);
	if(a==b)return;
	mx[b] = max(mx[b],mx[a]);
	mn[b] = min(mn[b],mn[a]);
	par[a] = b;
}
ll ans = 0;
int n = 0;
void solve(int l,int r){
	int r0 = r;
	int l0 = l;
	int rcost = 0;
	int lcost = 0;

	int rlast = r;
	int llast = l;
	while(r0 < n){
		if(mn[find(r0)] < l){ 
			rcost += 2*(r0 - rlast);
			break;
		}
		if(mx[find(r0)] > r0){
			rcost += 2*(r0 - rlast);
			r0 = mx[find(r0)];
			rlast = r0;
		}else r0++;
	}
	while(l0 >= 0){
		if(mx[find(l0)] > r){
			lcost += 2*(llast - l0);
			break;
		}
		if(mn[find(l0)] < l0){
			lcost += 2*(llast - l0);
			l0 = mn[find(l0)];
			llast = l0;
		}else l0--;
	}
	if(l0 == -1 && r0 == n){
		ans += lcost;
		ans += rcost;
		return;
	}

	ans += min(lcost,rcost);
	l = mn[find(l0)];
	r = mx[find(r0)];
	solve(l,r);
}
ll minimum_walk(vector<int> p, int s) {
	n = sz(p);
	for(int i=0;i<n;i++)ans+=abs(i-p[i]);
	for(int i=0;i<n;i++){
		par[i] = i;
		mn[i] = min(i,p[i]);
		mx[i] = max(i,p[i]);
	}

	for(int i=0;i<n;i++){
		int l = min(i,p[i]);
		int r = max(i,p[i]);
		if(l==r)continue;

		while(true){
			l = find(l);
			if(l >= r)break;
			unite(l,l+1);
		}
	}

	solve(s,s);
	return ans;	
}

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