Submission #403613

#	Time	Username	Problem	Language	Result	Execution time	Memory
403613		dxz05	Arranging Shoes (IOI19_shoes)	C++14	10 / 100	194 ms	24516 KiB

shoes

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

using namespace std;

typedef long long ll;

const int MAXN = 4e5 + 6e3;

map<int, vector<int>> mp;

int f[MAXN];

void add(int x, int y){
    x++;
    while (x < MAXN){
        f[x] += y;
        x += (-x & x);
    }
}

void add(int l, int r, int y){
    if (l > r) return;
    add(l, y);
    add(r + 1, -y);
}

int get(int x){
    x++;
    int sum = 0;
    while (x > 0){
        sum += f[x];
        x -= (-x & x);
    }
    return sum;
}

int get(int l, int r){
    return get(r) - get(l - 1);
}

long long count_swaps(vector<int> a) {
	int n = a.size();

	for (int i = 0; i < n; i++){
        mp[a[i]].push_back(i);
	}

    vector<bool> used(n, false);

    ll ans = 0;
    for (int i = 0; i < n; i++){
        if (used[i]) continue;

        int l = 0, r = mp[-a[i]].size() - 1;
        int ind, j = i + get(i);
        while (l <= r){
            int m = (l + r) >> 1;
            int x = mp[-a[i]][m];
            if (x + get(x) > j){
                ind = x;
                r = m - 1;
            } else l = m + 1;
        }

        used[ind] = true;
        ind += get(ind);

        ans += ind - j - 1;
        if (a[i] > 0) ans++;

        add(j + 1, ind - 1, 1);

    }

	return ans;
}

Compilation message (stderr)

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:67:13: warning: 'ind' may be used uninitialized in this function [-Wmaybe-uninitialized]
   67 |         ind += get(ind);
      |         ~~~~^~~~~~~~~~~

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