| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 488906 |
2021-11-20T19:21:58 Z |
dxz05 |
Islands (IOI08_islands) |
C++14 |
|
592 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>
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;
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];
struct node{
ll mx;
ll add;
node(){
mx = 0;
add = 0;
}
};
vector<node> tree;
struct SegTree{
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);
}
} ST;
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 = {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));
int v, u;
for (int i = 1; i < n; i++){
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;
for (int i = 1; i <= n; i++) parent[i] = i;
for (int i = 1; i <= n; i++){
cin >> f[i] >> w[i];
parent[find(i)] = find(f[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;
}
}
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:106:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
106 | while (size < a.size()) size *= 2;
| ~~~~~^~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
12 ms |
23884 KB |
Output is correct |
| 2 |
Correct |
13 ms |
23852 KB |
Output is correct |
| 3 |
Correct |
14 ms |
24012 KB |
Output is correct |
| 4 |
Correct |
13 ms |
23876 KB |
Output is correct |
| 5 |
Correct |
12 ms |
23920 KB |
Output is correct |
| 6 |
Correct |
13 ms |
23960 KB |
Output is correct |
| 7 |
Correct |
12 ms |
23960 KB |
Output is correct |
| 8 |
Correct |
12 ms |
23964 KB |
Output is correct |
| 9 |
Correct |
12 ms |
23884 KB |
Output is correct |
| 10 |
Correct |
13 ms |
23972 KB |
Output is correct |
| 11 |
Correct |
15 ms |
23884 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
14 ms |
23984 KB |
Output is correct |
| 2 |
Correct |
16 ms |
23912 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
13 ms |
24012 KB |
Output is correct |
| 2 |
Correct |
15 ms |
24444 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
23 ms |
25180 KB |
Output is correct |
| 2 |
Correct |
40 ms |
28044 KB |
Output is correct |
| 3 |
Correct |
21 ms |
25360 KB |
Output is correct |
| 4 |
Correct |
19 ms |
24560 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
44 ms |
29780 KB |
Output is correct |
| 2 |
Correct |
81 ms |
32604 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
91 ms |
37696 KB |
Output is correct |
| 2 |
Correct |
194 ms |
48608 KB |
Output is correct |
| 3 |
Correct |
228 ms |
62136 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
234 ms |
46692 KB |
Output is correct |
| 2 |
Correct |
322 ms |
80248 KB |
Output is correct |
| 3 |
Correct |
541 ms |
92300 KB |
Output is correct |
| 4 |
Correct |
502 ms |
116656 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
355 ms |
82804 KB |
Output is correct |
| 2 |
Runtime error |
592 ms |
131076 KB |
Execution killed with signal 9 |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
310 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
