제출 #294671

#제출 시각아이디문제언어결과실행 시간메모리
294671shayan_p고대 책들 (IOI17_books)C++17
12 / 100
25 ms24320 KiB
// Oh damn! Suddenly you're free to fly...
 
#include<bits/stdc++.h>
#include "books.h"
 
#define F first
#define S second
#define PB push_back
#define sz(s) int((s).size())
#define bit(n,k) (((n)>>(k))&1)
 
using namespace std;
 
typedef long long ll;
typedef pair<int,int> pii;
 
const int maxn = 1e6 + 10, mod = 1e9 + 7, inf = 1e9 + 10;

int pr[maxn], L[maxn], R[maxn];
int cnt[maxn];

int fnd(int u){
    return pr[u] < 0 ? u : pr[u] = fnd(pr[u]);
}
void mrg(int a, int b){
    if( (a = fnd(a)) == (b = fnd(b)) )
	return;
    if(pr[a] > pr[b])
	swap(a, b);
    L[a] = min(L[a], L[b]);
    R[a] = max(R[a], R[b]);
    pr[a]+= pr[b];
    pr[b] = a;	    
}

ll minimum_walk(vector<int> p, int s){
    memset(pr, -1, sizeof pr);
    iota(L, L + maxn, 0);
    iota(R, R + maxn, 0);
    
    int n = sz(p);
    ll ans = 0;
    for(int i = 0; i < n; i++){
	int l = i, r = p[i];
	if(l > r)
	    swap(l, r);
	ans+= r-l;
	mrg(l, r);

	cnt[l]++, cnt[r]--;	
    }
    int safar = 0, sum = 0;
    for(int i = 0; i < n-1; i++){
	sum+= cnt[i];
	safar+= (sum == 0 ? 1 : 0);
    }
    
    int iter = 0;
    int l = s, r = s;
    while(true){
	assert(++iter == 1);
	while(true){
	    bool is = 0;
	    while(r < R[fnd(s)])
		mrg(s, ++r), is = 1;
	    while(l > L[fnd(s)])
		mrg(s, --l), is = 1;
	    if(!is)
		break;
	}		
	int d1 = 0, d2 = 0;
	while(r < n && L[fnd(s)] <= L[fnd(r)]){
	    d2+= R[fnd(s)] < R[fnd(r)];
	    mrg(s, r);
	    r++;
	}
	while(l >= 0 && R[fnd(l)] <= R[fnd(s)]){
	    d1+= L[fnd(s)] > L[fnd(l)];
	    mrg(s, l);
	    l--;
	}
	if(l == -1 || r == n){
	    assert(l == -1 && r == n);
	    assert(d1 == 0);
	    assert(d2 == safar);
	    ans+= 2 * (d1 + d2);
	    break;
	}
	else{
	    ans+= 2 * min(d1 + 1, d2 + 1);
	    assert(fnd(l) == fnd(r));
	    mrg(s, l);
	    mrg(s, r);
	}	    
    }
    for(int i = 0; i < s && p[i] == i; i++){
	ans-= 2;
    }
    for(int i = n-1; i > s && p[i] == i; i--){
	ans-= 2;
    }
    return ans;
}
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