| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 489249 |
2021-11-21T18:14:09 Z |
dxz05 |
Islands (IOI08_islands) |
C++14 |
|
1224 ms |
131076 KB |
//#pragma GCC optimize("Ofast,O2,O3,unroll-loops")
//#pragma GCC target("avx2")
#include <iostream>
#include <vector>
#include <bitset>
#include <stack>
#include <algorithm>
#include <chrono>
#include <random>
using namespace std;
#define SZ(s) ((int)s.size())
#define all(x) (x).begin(), (x).end()
#define lla(x) (x).rbegin(), (x).rend()
#define MP make_pair
typedef long long ll;
const double eps = 0.000001;
const int MOD = 998244353;
const int INF = 1000000101;
const long long LLINF = 1223372000000000555;
const int N = 1e6 + 1;
const int M = 222;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
int f[N], w[N];
vector<int> cycle;
stack<int> st;
bitset<N> used;
inline void find_cycle(int x){
while (!st.empty()) st.pop();
cycle.clear();
while (true){
st.push(x);
used[x] = true;
if (used[f[x]]){
while (!st.empty()){
int y = st.top(); st.pop();
cycle.push_back(y);
if (y == f[x]) break;
}
return;
}
x = f[x];
}
}
int parent[N];
int find(const int x){
return (x == parent[x] ? x : parent[x] = find(parent[x]));
}
vector<int> g[N];
inline int A(const int &u, const int &v){
if (f[u] == v && f[v] != u) return w[u];
if (f[u] != v && f[v] == u) return w[v];
return max(w[u], w[v]);
}
int X; ll D;
void dfs(const int v, const int p, const ll d, const int c1, const int c2, const bool flag){
if (d > D) D = d, X = v;
for (int u : g[v]){
if (u != p && u != c1 && u != c2) dfs(u, v, d + A(u, v), c1, c2, flag);
}
if (flag) g[v].clear();
}
ll arr[N];
inline ll component(const int root){
find_cycle(root);
const int n = cycle.size();
ll ans = 0;
for (int i = 0; i < n; i++){
int v = cycle[i];
D = -1;
dfs(v, v, 0, cycle[(i + n - 1) % n], cycle[(i + 1) % n], false);
ans = max(ans, D);
arr[v] = D;
D = -1;
dfs(X, X, 0, cycle[(i + n - 1) % n], cycle[(i + 1) % n], true);
ans = max(ans, D);
}
if (n == 2){
int u = cycle[0], v = cycle[1];
ans = max(ans, arr[u] + arr[v] + A(u, v));
return ans;
}
vector<ll> a(n);
a[0] = {arr[cycle[0]]};
ll sum = 0;
for (int i = 1; i < n; i++){
sum += A(cycle[i - 1], cycle[i]);
a[i] = arr[cycle[i]] + sum;
}
sum += A(cycle[0], cycle.back());
// for (int x : cycle) cout << x << ' '; cout << endl;
// for (ll x : a) cout << x << ' '; cout << endl;
ans = max(ans, arr[cycle[0]] + *max_element(a.begin() + 1, a.end()));
vector<ll> sf(n, a.back());
for (int i = n - 2; i >= 0; i--) sf[i] = max(sf[i + 1], a[i]);
ll add = 0;
int v, u;
ll mx = 0;
for (int i = 1; i < n; i++){
v = cycle[i], u = cycle[i - 1];
add -= A(v, u);
mx = max(mx, a[i - 1] + sum);
ans = max(ans, arr[v] + add + mx);
if (i + 1 < n) ans = max(ans, arr[v] + add + sf[i + 1]);
mx = max(mx, a[i]);
// for (int j = 1; j <= n; j++) cout << ST.get(j, j) << ' '; cout << endl;
}
return ans;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
int n;
cin >> n;
for (int i = 1; i <= n; i++) parent[i] = i;
for (int i = 1; i <= n; i++){
cin >> f[i] >> w[i];
if (rng() & 1) parent[find(i)] = find(f[i]); else
parent[find(f[i])] = find(i);
if (f[f[i]] != i){
g[i].push_back(f[i]);
g[f[i]].push_back(i);
}
}
bitset<N> comp;
ll ans = 0;
for (int i = 1; i <= n; i++){
if (!comp[find(i)]){
comp[find(i)] = true;
const ll cur = component(i);
ans += cur;
}
}
cout << ans;
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
12 ms |
23884 KB |
Output is correct |
| 2 |
Correct |
12 ms |
23964 KB |
Output is correct |
| 3 |
Correct |
13 ms |
23884 KB |
Output is correct |
| 4 |
Correct |
12 ms |
23920 KB |
Output is correct |
| 5 |
Correct |
13 ms |
23884 KB |
Output is correct |
| 6 |
Correct |
12 ms |
23892 KB |
Output is correct |
| 7 |
Correct |
15 ms |
23832 KB |
Output is correct |
| 8 |
Correct |
12 ms |
23844 KB |
Output is correct |
| 9 |
Correct |
17 ms |
23908 KB |
Output is correct |
| 10 |
Correct |
13 ms |
23860 KB |
Output is correct |
| 11 |
Correct |
13 ms |
23884 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
13 ms |
24012 KB |
Output is correct |
| 2 |
Correct |
12 ms |
24032 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
12 ms |
24036 KB |
Output is correct |
| 2 |
Correct |
14 ms |
24140 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
18 ms |
24736 KB |
Output is correct |
| 2 |
Correct |
35 ms |
26052 KB |
Output is correct |
| 3 |
Correct |
28 ms |
25032 KB |
Output is correct |
| 4 |
Correct |
17 ms |
24504 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
34 ms |
27196 KB |
Output is correct |
| 2 |
Correct |
46 ms |
29408 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
86 ms |
35220 KB |
Output is correct |
| 2 |
Correct |
88 ms |
37372 KB |
Output is correct |
| 3 |
Correct |
111 ms |
41608 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
136 ms |
44808 KB |
Output is correct |
| 2 |
Correct |
169 ms |
57020 KB |
Output is correct |
| 3 |
Correct |
226 ms |
61732 KB |
Output is correct |
| 4 |
Correct |
234 ms |
69140 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
293 ms |
74860 KB |
Output is correct |
| 2 |
Correct |
812 ms |
86196 KB |
Output is correct |
| 3 |
Correct |
257 ms |
65340 KB |
Output is correct |
| 4 |
Correct |
337 ms |
81892 KB |
Output is correct |
| 5 |
Correct |
328 ms |
83616 KB |
Output is correct |
| 6 |
Correct |
1224 ms |
67904 KB |
Output is correct |
| 7 |
Correct |
363 ms |
94696 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
338 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
