Submission #399307

#	Time	Username	Problem	Language	Result	Execution time	Memory
399307		mshandilya	Arranging Shoes (IOI19_shoes)	C++14	10 / 100	1 ms	204 KiB

shoes

#include <bits/stdc++.h>
#include "shoes.h"
using namespace std;

long long count_swaps(std::vector<int> s) {
	long long sort_inversions = 0, total_inversions = 0;
    int N = (s.size()/2), left_pair = 0, right_pair = 0, cpos; 
    std::vector<int> position(N), BIT(N);
    std::vector<std::queue<int>> compensated_inversions(N+1, queue<int> ()), positional_queue(N+1, queue<int> ());
    for(int i = 2*N-1; i>=0; i--) {
        if(s[i]<0 && positional_queue[abs(s[i])].empty()) {
            compensated_inversions[abs(s[i])].push(left_pair);
            left_pair++;
        }
        else if(s[i]<0) {
            position[N-1-left_pair] = N-positional_queue[abs(s[i])].front();
            positional_queue[abs(s[i])].pop();
            left_pair++;
        }
        else if(!compensated_inversions[s[i]].empty()) {
            total_inversions += left_pair - compensated_inversions[s[i]].front();
            right_pair++;
            position[N-compensated_inversions[s[i]].front()-1] = N-right_pair;
            compensated_inversions[s[i]].pop();
        }
        else {
            right_pair++;
            positional_queue[s[i]].push(right_pair);
        }
    }
    for(int i = 0, j; i<N; i++) {
    	j = i+1;
    	while(j>0) {
    		BIT[j-1]++;
    		j -= (j & (-j));
    	}
    }
    for(int i = N-1; i>=0; i--) {
    	cpos = position[i] + 2;
    	while(cpos<=N) {
    		sort_inversions += BIT[cpos-1];
    		cpos += (cpos & (-cpos));
    	}
    	cpos = position[i] + 1;
    	while(cpos>0) {
    		BIT[cpos-1]--;
    		cpos -= (cpos & (-cpos));
    	}
    }
	return (total_inversions+sort_inversions);
}

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