| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 488921 |
2021-11-20T19:43:35 Z |
dxz05 |
Islands (IOI08_islands) |
C++14 |
|
929 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 + 5;
const int M = 222;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
int f[N]; int w[N];
bitset<N> used;
stack<int> st;
vector<int> cycle;
void dfs0(int v){
if (!cycle.empty()) return;
used[v] = true;
st.push(v);
if (used[f[v]]){
while (!st.empty()){
int x = st.top(); st.pop();
cycle.push_back(x);
if (x == f[v]) break;
}
return;
}
if (!cycle.empty()) return;
dfs0(f[v]);
if (!st.empty()) st.pop();
}
int parent[N];
int find(int x){
return (x == parent[x] ? x : parent[x] = find(parent[x]));
}
vector<int> g[N];
bitset<N> incycle;
int A(int u, 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]);
}
void dfs(int v, int p, ll d, int root, vector<int> &tree, vector<ll> &dist, bool flag){
tree.push_back(v);
dist.push_back(d);
for (int u : g[v]){
if (u != p){
if (u == root || !incycle[u]) dfs(u, v, d + A(u, v), root, tree, dist, flag);
}
}
if (flag) g[v].clear();
}
ll arr[N];
ll component(int root){
cycle.clear();
while (!st.empty()) st.pop();
dfs0(root);
for (int v : cycle){
incycle[v] = true;
}
ll ans = 0;
vector<int> tree; vector<ll> dist;
for (int v : cycle){
dfs(v, v, 0, v, tree, dist, false);
int i = max_element(all(dist)) - dist.begin();
ans = max(ans, dist[i]);
arr[v] = dist[i];
int u = tree[i];
tree.clear(); dist.clear();
dfs(u, u, 0, v, tree, dist, true);
ans = max(ans, *max_element(all(dist)));
tree.clear(), dist.clear();
}
int n = cycle.size();
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;
}
void solve(int TC) {
int n;
scanf("%d", &n);
for (int i = 1; i <= n; i++) parent[i] = i;
for (int i = 1; i <= n; i++){
scanf("%d %d", 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].emplace_back(f[i]);
g[f[i]].emplace_back(i);
}
}
bitset<N> comp;
ll ans = 0;
for (int i = 1; i <= n; i++){
if (!comp[find(i)]){
comp[find(i)] = true;
ll cur = component(i);
ans += cur;
}
}
printf("%I64d", ans);
}
int main() {
// ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#ifdef dddxxz
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
int TC = 1;
// cin >> TC;
for (int test = 1; test <= TC; test++) {
//debug(test);
//cout << "Case #" << test << ": ";
solve(test);
}
return 0;
}
Compilation message
islands.cpp: In function 'void solve(int)':
islands.cpp:181:17: warning: format '%d' expects argument of type 'int', but argument 2 has type 'll' {aka 'long long int'} [-Wformat=]
181 | printf("%I64d", ans);
| ~~~~^ ~~~
| | |
| int ll {aka long long int}
| %I64lld
islands.cpp:156:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
156 | scanf("%d", &n);
| ~~~~~^~~~~~~~~~
islands.cpp:161:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
161 | scanf("%d %d", f + i, w + i);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
12 ms |
23884 KB |
Output is correct |
| 2 |
Correct |
13 ms |
23960 KB |
Output is correct |
| 3 |
Incorrect |
12 ms |
23936 KB |
Output isn't correct |
| 4 |
Correct |
13 ms |
23836 KB |
Output is correct |
| 5 |
Correct |
13 ms |
23844 KB |
Output is correct |
| 6 |
Correct |
12 ms |
23852 KB |
Output is correct |
| 7 |
Correct |
15 ms |
23832 KB |
Output is correct |
| 8 |
Incorrect |
13 ms |
23856 KB |
Output isn't correct |
| 9 |
Incorrect |
12 ms |
23924 KB |
Output isn't correct |
| 10 |
Correct |
13 ms |
23884 KB |
Output is correct |
| 11 |
Incorrect |
13 ms |
23952 KB |
Output isn't correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
13 ms |
24012 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
13 ms |
23992 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
20 ms |
24912 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
36 ms |
28900 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
91 ms |
36776 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
184 ms |
46220 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
348 ms |
84652 KB |
Output is correct |
| 2 |
Incorrect |
929 ms |
131072 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
392 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
