| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 488801 |
2021-11-20T13:36:14 Z |
dxz05 |
Islands (IOI08_islands) |
C++14 |
|
656 ms |
131076 KB |
#pragma GCC optimize("Ofast,O2,O3,unroll-loops")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
using namespace std;
#define SZ(s) ((int)s.size())
#define all(x) (x).begin(), (x).end()
#define lla(x) (x).rbegin(), (x).rend()
clock_t startTime;
double getCurrentTime() {
return (double) (clock() - startTime) / CLOCKS_PER_SEC;
}
#define MP make_pair
typedef long long ll;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
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;
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]));
}
void unite(int x, int y){
x = find(x);
y = find(y);
if (x == y) return;
if (rng() & 1) swap(x, y);
parent[x] = y;
}
vector<pair<int, int>> g[N];
bitset<N> incycle;
void dfs(int v, int p, ll d, int root, vector<int> &tree, vector<ll> &dist){
tree.push_back(v);
dist.push_back(d);
for (auto now : g[v]){
int u = now.first; int W = now.second;
if (u != p){
if (u == root || !incycle[u]) dfs(u, v, d + W, root, tree, dist);
}
}
}
ll arr[N];
struct SegTree{
struct node{
ll mx;
ll add;
node(){
mx = 0;
add = 0;
}
};
vector<node> tree;
int size = 1;
void build(int v, int tl, int tr, vector<ll> &a){
if (tl == tr){
tree[v].mx = a[tl - 1];
tree[v].add = 0;
return;
}
int tm = (tl + tr) >> 1;
build(v + v, tl, tm, a);
build(v + v + 1, tm + 1, tr, a);
tree[v].mx = max(tree[v + v].mx, tree[v + v + 1].mx);
}
void init(vector<ll> &a){
while (size < a.size()) size *= 2;
tree.assign(size * 2 + 5, node());
build(1, 1, size, a);
}
void push(int v){
if (tree[v].add == 0) return;
tree[v + v].mx += tree[v].add;
tree[v + v + 1].mx += tree[v].add;
tree[v + v].add += tree[v].add;
tree[v + v + 1].add += tree[v].add;
tree[v].add = 0;
}
void add(int l, int r, ll val, int v, int tl, int tr){
if (l <= tl && tr <= r){
tree[v].mx += val;
tree[v].add += val;
return;
}
if (tl > r || tr < l) return;
push(v);
int tm = (tl + tr) >> 1;
add(l, r, val, v + v, tl, tm);
add(l, r, val, v + v + 1, tm + 1, tr);
tree[v].mx = max(tree[v + v].mx, tree[v + v + 1].mx);
}
void add(int l, int r, ll val){
add(l, r, val, 1, 1, size);
}
ll get(int l, int r, int v, int tl, int tr){
if (l <= tl && tr <= r) return tree[v].mx;
if (l > tr || r < tl) return 0;
push(v);
int tm = (tl + tr) >> 1;
return max(get(l, r, v + v, tl, tm), get(l, r, v + v + 1, tm + 1, tr));
}
ll get(int l, int r){
return get(l, r, 1, 1, size);
}
ll get(){
return tree[1].mx;
}
} ST;
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]);
}
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){
tree.clear();
dist.clear();
dfs(v, v, 0, v, tree, dist);
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);
ans = max(ans, *max_element(all(dist)));
}
int n = cycle.size();
if (n == 2){
int u = cycle[0], v = cycle[1];
ans = max(ans, arr[u] + arr[v] + max(w[u], w[v]));
return ans;
}
vector<ll> a = {arr[cycle[0]]};
ll sum = 0;
for (int i = 1; i < n; i++){
sum += A(cycle[i - 1], cycle[i]);
a.push_back(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;
ST.init(a);
ans = max(ans, arr[cycle[0]] + ST.get(2, n));
for (int i = 1; i < n; i++){
int v = cycle[i], u = cycle[i - 1];
ST.add(1, n, -A(v, u));
ST.add(i, i, sum);
ans = max(ans, arr[v] + max(ST.get(1, i), ST.get(i + 2, n)));
// for (int j = 1; j <= n; j++) cout << ST.get(j, j) << ' '; cout << endl;
}
return ans;
}
void solve(int TC) {
int n;
cin >> n;
iota(parent + 1, parent + n + 1, 1);
for (int i = 1; i <= n; i++){
cin >> f[i] >> w[i];
unite(i, f[i]);
if (f[f[i]] != i){
g[i].emplace_back(f[i], w[i]);
g[f[i]].emplace_back(i, w[i]);
}
}
set<int> comp;
ll ans = 0;
for (int i = 1; i <= n; i++){
if (comp.find(find(i)) == comp.end()){
comp.insert(find(i));
ll cur = component(i);
ans += cur;
}
}
cout << 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 member function 'void SegTree::init(std::vector<long long int>&)':
islands.cpp:112:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
112 | while (size < a.size()) size *= 2;
| ~~~~~^~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
13 ms |
23884 KB |
Output is correct |
| 2 |
Correct |
15 ms |
23884 KB |
Output is correct |
| 3 |
Correct |
16 ms |
23924 KB |
Output is correct |
| 4 |
Correct |
13 ms |
23756 KB |
Output is correct |
| 5 |
Correct |
14 ms |
23840 KB |
Output is correct |
| 6 |
Correct |
13 ms |
23716 KB |
Output is correct |
| 7 |
Correct |
14 ms |
23752 KB |
Output is correct |
| 8 |
Correct |
14 ms |
23844 KB |
Output is correct |
| 9 |
Correct |
14 ms |
23848 KB |
Output is correct |
| 10 |
Correct |
14 ms |
23744 KB |
Output is correct |
| 11 |
Correct |
15 ms |
23756 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
13 ms |
23976 KB |
Output is correct |
| 2 |
Correct |
14 ms |
23956 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
15 ms |
23884 KB |
Output is correct |
| 2 |
Correct |
15 ms |
24268 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
22 ms |
25060 KB |
Output is correct |
| 2 |
Correct |
36 ms |
28112 KB |
Output is correct |
| 3 |
Correct |
23 ms |
25320 KB |
Output is correct |
| 4 |
Correct |
17 ms |
24504 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
48 ms |
29976 KB |
Output is correct |
| 2 |
Correct |
79 ms |
33020 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
90 ms |
38428 KB |
Output is correct |
| 2 |
Correct |
180 ms |
48824 KB |
Output is correct |
| 3 |
Correct |
193 ms |
63560 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
234 ms |
48292 KB |
Output is correct |
| 2 |
Correct |
286 ms |
83352 KB |
Output is correct |
| 3 |
Correct |
490 ms |
92280 KB |
Output is correct |
| 4 |
Correct |
465 ms |
120348 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
297 ms |
97984 KB |
Output is correct |
| 2 |
Runtime error |
656 ms |
131076 KB |
Execution killed with signal 9 |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
322 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
