| # |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
| 488741 |
2021-11-20T10:50:46 Z |
dxz05 |
Islands (IOI08_islands) |
C++14 |
|
146 ms |
131076 KB |
#pragma GCC optimize("Ofast,O2,O3,unroll-loops")
#pragma GCC target("avx2")
#include <bits/stdc++.h>
using namespace std;
void debug_out() { cerr << endl; }
template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
cerr << "[" << H << "]";
debug_out(T...);
}
#ifdef dddxxz
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
#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 + 3e2;
const int M = 222;
int f[N], w[N];
bool used[N];
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<int> comp[N];
vector<pair<int, ll>> g[N];
bool incycle[N];
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; ll 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){
size = a.size();
tree.assign(size * 6, 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;
map<int, ll> A[N];
ll component(vector<int> vec){
cycle.clear();
while (!st.empty()) st.pop();
dfs0(vec.front());
for (int v : cycle){
incycle[v] = true;
}
ll ans = 0;
for (int v : cycle){
vector<int> tree; vector<ll> dist;
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, max(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;
debug(sum);
ST.init(a);
ans = max(ans, arr[cycle[0]] + ST.get());
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;
ST.add(i, i, A[v][u]);
}
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 (A[i].find(f[i]) == A[i].end()){
g[i].emplace_back(f[i], w[i]);
g[f[i]].emplace_back(i, w[i]);
A[i][f[i]] = w[i];
A[f[i]][i] = w[i];
}
}
for (int i = 1; i <= n; i++){
comp[find(i)].push_back(i);
}
ll ans = 0;
for (int i = 1; i <= n; i++){
if (!comp[i].empty()){
ll cur = component(comp[i]);
debug(i, cur);
ans += cur;
}
}
cout << ans;
}
int main() {
startTime = clock();
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);
}
cerr << endl << "Time: " << int(getCurrentTime() * 1000) << " ms" << endl;
return 0;
}
Compilation message
islands.cpp: In function 'll component(std::vector<int>)':
islands.cpp:19:20: warning: statement has no effect [-Wunused-value]
19 | #define debug(...) 42
| ^~
islands.cpp:226:5: note: in expansion of macro 'debug'
226 | debug(sum);
| ^~~~~
islands.cpp: In function 'void solve(int)':
islands.cpp:19:20: warning: statement has no effect [-Wunused-value]
19 | #define debug(...) 42
| ^~
islands.cpp:272:13: note: in expansion of macro 'debug'
272 | debug(i, cur);
| ^~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
49 ms |
94188 KB |
Output is correct |
| 2 |
Incorrect |
51 ms |
94376 KB |
Output isn't correct |
| 3 |
Correct |
51 ms |
94388 KB |
Output is correct |
| 4 |
Incorrect |
50 ms |
94276 KB |
Output isn't correct |
| 5 |
Incorrect |
50 ms |
94208 KB |
Output isn't correct |
| 6 |
Correct |
50 ms |
94276 KB |
Output is correct |
| 7 |
Correct |
50 ms |
94252 KB |
Output is correct |
| 8 |
Incorrect |
51 ms |
94256 KB |
Output isn't correct |
| 9 |
Correct |
50 ms |
94312 KB |
Output is correct |
| 10 |
Correct |
52 ms |
94416 KB |
Output is correct |
| 11 |
Correct |
55 ms |
94244 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
54 ms |
94508 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
52 ms |
94584 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
70 ms |
97908 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
121 ms |
108324 KB |
Output is correct |
| 2 |
Incorrect |
146 ms |
118896 KB |
Output isn't correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
135 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
123 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
142 ms |
131072 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
126 ms |
131076 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
