| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 199325 | mythos | Arranging Shoes (IOI19_shoes) | C++14 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
#include "shoes.h"
using namespace std;
struct Fenwick {
vector<int> a;
int n;
Fenwick(int n): n(n), a(vector<int>(n, 0)) {}
int get(int j) {
int res = 0;
for (; j >= 0; j = (j & (j + 1)) - 1) res += a[j];
return res;
}
int get(int l, int r) {
return (count(r) - count(l - 1));
}
void set(int id) {
for (; id < n; id = id | (id + 1)) a[id]++;
}
};
vector<int> create_ind(int n, vector<int> &s) {
vector<int> ind(2 * n + 1);
for (int i = 0; i < 2 * n; i++) ind[s[i] + n] = i;
return ind;
}
long long count_adj(int n, vector<int> &s) {
vector<int> id = create_ind(n, s);
Fenwick fw = Fenwick(2 * n);
long long ans = 0;
for (int i = 0; i < 2 * n; i++) {
if (s[i] != 0) {
int pos = id[n - s[i]];
ans += pos - i - fw.get(i, pos) - (s[i] < 0 ? 1 : 0);
s[pos] = 0;
fw.set(pos);
}
}
return ans;
}
void change(vector<int> &v) {
int n = (int) v.size() / 2;
vector<int> cnt(n, 0);
for (int i = 0; i < 2 * n; i++) {
if (v[i] > 0) cnt[v[i] - 1]++;
}
for (int i = 1; i < n; i++) cnt[i] += cnt[i - 1];
vector<int> cntl = cnt, cntr = cnt;
for (int i = 0; i < 2 * n; i++) {
if (v[i] > 0) v[i] = (--cntr[v[i] - 1]) + 1;
else v[i] -= - ((--cntl[-v[i] - 1]) + 1);
}
}
long long count_swaps(vector<int> s) {
change(s);
int n = (int) s.size() / 2;
return count_adj(n, s);
}