Submission #935157

#	Time	Username	Problem	Language	Result	Execution time	Memory
935157		Lobo	Ancient Books (IOI17_books)	C++17	100 / 100	234 ms	187220 KiB

books

#include "books.h"
#include<bits/stdc++.h>
using namespace std;
const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
const int maxn = 1e6+10;

int n;
int ds[maxn], dsz[maxn], dsl[maxn], dsr[maxn];
int nxr[maxn], costr[maxn];

int find(int v) {
	if(v == ds[v]) return v;
	return ds[v] = find(ds[v]);
}

void join(int u, int v) {
	u = find(u);
	v = find(v);
	if(u == v) return;

	if(dsz[u] < dsz[v]) swap(u,v);
	dsz[u]+= dsz[v];
	dsl[u] = min(dsl[u],dsl[v]);
	dsr[u] = max(dsr[u],dsr[v]);
	ds[v] = u;
}

int L,R;
map<int,int> dp[maxn];
int sol(int l, int r) {
	if(dp[l].count(r)) return dp[l][r];
	if(l == L && r == R) return dp[l][r] = 0;

	dp[l][r] = inf;
	if(l > L) dp[l][r] = min(dp[l][r],2+sol(dsl[find(l-1)],max(r,dsr[find(l-1)])));
	if(r < R) dp[l][r] = min(dp[l][r],2*costr[find(r)]+sol(min(l,dsl[find(nxr[find(r)])]),dsr[find(nxr[find(r)])]));
	return dp[l][r];
}

long long minimum_walk(vector<int32_t> p, int32_t s) {
	// return 0;

	n = p.size();

	for(int i = 0; i < n; i++) {
		ds[i] = i;
		dsz[i] = 1;
		dsl[i] = i;
		dsr[i] = i;
	}

	for(int i = 0; i < n; i++) {
		join(i,p[i]);
	}

	int itl = s;
	while(itl != n) {
		int itr = itl;
		int cur = itl;
		while(cur <= itr) {
			itr = max(itr,dsr[find(cur)]);
			cur++;
		}
		for(int i = itl; i < itr; i++) {
			join(i,i+1);
		}
		itl = itr+1;
	}

	int itr = s;
	while(itr >= 0) {
		int itl = itr;
		int cur = itr;
		while(cur >= itl) {
			itl = min(itl,dsl[find(cur)]);
			cur--;
		}
		for(int i = itl; i < itr; i++) {
			join(i,i+1);
		}
		itr = itl-1;
	}

	L = 0;
	R = n-1;
	while(L < s && dsz[find(L)] == 1) L++;
	while(R > s && dsz[find(R)] == 1) R--;

	nxr[find(R)] = R;
	costr[find(R)] = 0;
	for(int i = R-1; i >= s; i--) {
		if(find(i) == find(i+1)) {
			continue;
		}
		else if(dsl[find(i+1)] < s or dsr[find(i+1)] == R) {
			nxr[find(i)] = i+1;
			costr[find(i)] = 1;
		}
		else {
			nxr[find(i)] = nxr[find(i+1)];
			costr[find(i)] = costr[find(i+1)]+1;
		}
	}

	// nxl[find(L)] = L;
	// costl[find(L)] = 0;
	// for(int i = L+1; i <= s; i++) {
	// 	if(find(i) == find(i-1)) {
	// 		continue;
	// 	}
	// 	else if()
	// }



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

	return ans+sol(dsl[find(s)],dsr[find(s)]);
}

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