Submission #371135

#	Time	Username	Problem	Language	Result	Execution time	Memory
371135		doowey	Ancient Books (IOI17_books)	C++14	50 / 100	210 ms	20184 KiB

books

#include <bits/stdc++.h>
#include "books.h"

using namespace std;

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

#define fi first
#define se second
#define mp make_pair

int n;
const int N = (int)1e6 + 100;
int lef[N], rig[N];
bool vis[N];
bool has[N];

int tl, tr;


void extend(int &li, int &ri){
    int ni = min(lef[li],lef[ri]);
    int nj = max(rig[li],rig[ri]);
    while(li > ni || ri < nj){
        if(li > ni){
            li--;
            ni = min(ni, lef[li]);
            nj = max(nj, rig[li]);
        }
        else{
            ri++;
            ni = min(ni, lef[ri]);
            nj = max(nj, rig[ri]);
        }
    }
}

int disl[N];
int disr[N];

int st;

int solve(int li, int ri){
    int cnt = 0;
    extend(li, ri);
    int ai, aj;
    while(li != tl || ri != tr){
        if(li == tl){
            cnt += 2;
            ri ++ ;
        }
        else if(ri == tr){
            cnt += 2;
            li -- ;
        }
        else{
            int il = li;
            int ir = ri;
            int ca = 0;
            bool valid = false;
            int low=li, high=ri;
            while(il > tl){
                il--;
                ca += 2;
                extend(il, ir);
                if(ir > ri){
                    valid = true;
                    break;
                }
            }
            if(!valid){
                li=tl;
                cnt+=ca;
                break;
            }
            low = min(low, il);
            high = max(high, ir);

            il = li;
            ir = ri;
            int cb = 0;
            valid = false;
            while(ir < tr){
                ir++;
                cb += 2;
                extend(il, ir);
                if(il < li){
                    valid = true;
                    break;
                }
            }
            if(!valid){
                ri=tr;
                cnt += cb;
                extend(li, ri);
                continue;
            }
            low = min(low, il);
            high = max(high, ir);
            cnt += min(ca, cb);
            li = low;
            ri = high;
        }
        extend(li,ri);
    }
    return cnt;
}
long long minimum_walk(vector<int> p, int s) {
	n = p.size();
	st = s;
	int id;
	int low, high;
	ll sol = 0;
    tl = tr = s;
	for(int i = 0 ; i < n; i ++ ){
        sol += abs(p[i] - i);
        if(!vis[i]){
            vector<int> cyc;
            id = i;
            while(!vis[id]){
                vis[id]=true;
                cyc.push_back(id);
                id=p[id];
            }
            low = n-1;
            high = 0;
            for(auto x : cyc){
                low = min(low, x);
                high = max(high, x);
            }
            for(auto x : cyc){
                lef[x] = low;
                rig[x] = high;
            }
        }
        if(p[i] != i){
            tl = min(tl, i);
            tr = max(tr, i);
        }
	}
	return sol + solve(s, s);
}

Compilation message (stderr)

books.cpp: In function 'int solve(int, int)':
books.cpp:47:9: warning: unused variable 'ai' [-Wunused-variable]
   47 |     int ai, aj;
      |         ^~
books.cpp:47:13: warning: unused variable 'aj' [-Wunused-variable]
   47 |     int ai, aj;
      |             ^~

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