| # | 제출 시각 | 아이디 | 문제 | 언어 | 결과 | 실행 시간 | 메모리 |
|---|---|---|---|---|---|---|---|
| 1305819 | ayaz | Arranging Shoes (IOI19_shoes) | C++20 | 0 ms | 0 KiB |
long long count_swaps(std::vector<int> s) {
vector<int> a = s;
int n = isz(a);
#define int long long
bool ok = true;
set<int> st;
for (int i = 0; i < n / 2; i++) {
ok &= (a[i] + a[i + n / 2] == 0);
ok &= (a[i] < 0);
st.insert(abs(a[i]));
}
if (ok) {
return (n / 2) * (n / 2 - 1) / 2;
}
if (isz(st) == 1) {
int ans = 0;
set<int> pos[2];
for (int i = 0; i < n; i++) {
pos[a[i] < 0 ? 0 : 1].insert(i);
}
for (int i = 0; i < n; i++) {
if (i % 2 == 0 && a[i] > 0) {
auto it = pos[0].upper_bound(i);
ans += *it - i;
swap(a[i], a[*it]);
pos[0].erase(it);
pos[1].erase(pos[1].find(i));
pos[0].insert(i);
pos[1].insert(*it);
continue;
}
if (i % 2 == 1 && a[i] < 0) {
auto it = pos[1].upper_bound(i);
ans += *it - i;
swap(a[i], a[*it]);
pos[1].erase(it);
pos[0].erase(pos[0].find(i));
pos[1].insert(i);
pos[0].insert(*it);
}
}
return ans;
}
if (n == 2) {
return (a[0] > 0);
}
a = s;
int ans = 0;
for (int i = 0; i < n; i++) {
if (i % 2 == 0 && a[i] > 0) {
int d = 1e9;
for (int j = i + 1; j < n; j++) {
if (a[j] + a[i] == 0) {
d = j;
break;
}
}
ans += (d - i);
for (int j = d; j > i; j--) swap(a[j], a[j - 1]);
continue;
}
if (i % 2 == 1 && (a[i] < 0 || (a[i - 1] + a[i]) != 0)) {
int d = 1e9;
for (int j = i + 1; j < n; j++) {
if (a[j] + a[i - 1] == 0) {
d = j;
break;
}
}
ans += (d - i);
for (int j = d; j > i; j--) swap(a[j], a[j - 1]);
}
}
for (int i = 0; i < n; i += 2) {
ans += (a[i] > 0);
}
return ans;
}