Submission #620080

#	Time	Username	Problem	Language	Result	Execution time	Memory
620080		serize	Arranging Shoes (IOI19_shoes)	C++17	30 / 100	48 ms	6352 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
#include <cstdio>
#include <cassert>
#define all(x) x.begin(),x.end()
#define lowbit(x) x&(-x)

using namespace std;

const int NMAX = 4e5+2;

vector<int> fenwick(NMAX);

inline void add(int k, int v){
    if(k <= 0) return;
    while(k < NMAX){
        fenwick[k] += v;
        k += lowbit(k);
    }
}

inline int read(int k){
    int sum = 0;
    while(k > 0){
        sum+=fenwick[k];
        k -= lowbit(k);
    }
    return sum;
}

long long count_swaps(std::vector<int> s) {
    int n = (int)s.size();
    if(n <= 16){
        vector<int> neg;
        for(int i = 0; i < n; i++){
            if(s[i] < 0){
                neg.push_back(i);
            }
        }
        const int MAX = 16;
        bitset<MAX> mark;
        int ans = INT32_MAX;
        do{
            mark.reset();
            vector<int> ar(n);
            int aux = 0;
            for(int i = 0; i < n/2; i++){
                ar[aux] = neg[i];
                for(int j = 0; j < n; j++){
                    if(mark[j] == false and s[j] == -s[ar[aux]]){
                        ar[aux+1] = j;
                        mark[j] = true;
                        break;
                    }
                }
                aux += 2;
            }
            vector<int> pos(n), num(n);
            for(int i = 0; i < n; i++) pos[i] = num[i] = i;
            int swp = 0;
            for(int i = 0; i < n; i++){
                swp += abs(i-pos[ar[i]]);
                if(pos[ar[i]] < i){
                    for(int j = pos[ar[i]]+1; j <= i; j++){
                        pos[ num[j] ]--;
                    }
                    pos[ ar[i] ] = i;
                }
                if(i < pos[ar[i]]){
                    for(int j = pos[ar[i]]-1; j >= i; j--){
                        pos[num[j]]++;
                    }
                    pos[ ar[i] ] = i;
                }
                for(int i = 0; i < n; i++) num[pos[i]] = i;
            }
            ans = min(ans,swp);
            
        }while(next_permutation(all(neg)));
            return ans;
    }
    else{
        queue<int> neg, pos;
        for(int i = 0; i < n; i++){
            if(s[i] < 0) neg.push(i);
            else pos.push(i);
        }
        vector<int> ar(n);
        for(int i = 0; i < n-1; i+=2){
            ar[i] = neg.front(); neg.pop();
            ar[i+1] = pos.front(); pos.pop();
        }
        for(int i = 2; i <= n; i++) add(i,1);
        /*cout << "this is the arr: \n"; 
        for(int i = 0; i < n; i++) cout << ar[i] << " ";
        cout << "\n";*/
        int l = 0, r = n-1;
        int swp = 0;
        while(l < r){
            int position = read(ar[l]+1);
            //cout << "L: " << l << "   num of the ar: " << ar[l] << "    position: " << position << "\n"; 
            swp += abs(position-l);
            add(l+1,1);
            add(position+1,-1);
            l++;
            position = read(ar[r]+1);
            //cout << "R: "  << r << "  num of the ar: " << ar[r] << "    position: " << position << "\n";
            swp += abs(position-r);
            add(r+2,1);
            add(position+1,-1);
            r--;
        }
        return swp;
    }
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 15