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Submission #440045

# Submission time Handle Problem Language Result Execution time Memory
440045 2021-07-01T14:07:08 Z dutch Islands (IOI08_islands) C++17
90 / 100
 1014 ms 131076 KB 
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define w (a[e][1])
#define V() (e == u ? a[e][0] : e)
#define v V()
#define E u
 
const int LIM = 1e6;
 
vector<int> g[LIM];
array<int, 2> a[LIM];
int r, p[LIM];
ll d[LIM], s[LIM], best;
bitset<LIM> vis;
 
void findCycle(int u, int par){
	vis[u] = 1;
	for(int e : g[u]) if(e != par){
		if(vis[v]) return void(r = e + (vis[u] = 0));
		findCycle(v, e);
		if(r >= 0) break;
	}
	if(u != par){
		if(vis[a[u][0]]) return void(r = u + (vis[u] = 0));
		findCycle(a[u][0], u);
	}
	vis[u] = 0;
}
 
int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	int n; cin >> n;
 
	for(int i=0; i<n; ++i){
		cin >> a[i][0] >> a[i][1]; --a[i][0];
		g[a[i][0]].push_back(i);
		// g[i].push_back(i);
	}
	fill(p, p+n, -1);
 
	ll ans = 0;
 
	for(int z=0; z<n; ++z){
		if(vis[z]) continue;
		r = -1, best = 0;
		findCycle(z, -1);
		assert(r >= 0);

		stack<int> st; st.push(r);

		while(!st.empty()){
			int u = st.top();
			if(!vis[u]){
				vis[u] = 1, s[u] = d[u];
				for(int e : g[u]) if(e != r && !vis[v]){
					p[v] = u;
					d[v] = d[u] + (ll)w;
					st.push(v);
				}
				if(u != r && !vis[a[u][0]]){
					p[a[u][0]] = u;
					d[a[u][0]] = d[u] + (ll)a[u][1];
					st.push(a[u][0]);
				}
			}else{
				ll curr = 0;
				for(int e : g[u]) if(e != r){
					s[u] = max(s[u], s[v]);
					best = max(best, curr + s[v] - d[u]);
					curr = max(curr, s[v] - d[u]);
				}
				if(u != r){
					s[u] = max(s[u], s[a[u][0]]);
					best = max(best, curr + s[a[u][0]] - d[u]);
					curr = max(curr, s[a[u][0]] - d[u]);
				}
				st.pop();
			}
		}
 
		int u = a[r][0], last = -1;
		while(1){
			vis[u] = 0;
			s[u] = d[u];
			for(int e : g[u])
				if(e != r && v != p[u] && v != last) s[u] = max(s[u], s[v]);
			if(u != r && a[u][0] != p[u] && a[u][0] != last) s[u] = max(s[u], s[a[u][0]]);
 
			if(u == r) break;
			last = u;
			u = p[u];
		}
		u = r;
		while(1){
			vis[u] = 1;
			for(int e : g[u])
				if(e != r && v != p[u] && !vis[v]) last = v;
			if(u != r && a[u][0] != p[u] && !vis[a[u][0]]) last = a[u][0];
 
			s[last] = max(s[last], s[u]);
 
			if(u == a[r][0]) break;
			u = last;
			last = -1;
		}
 
		u = a[r][0], last = -1;
		ll res = 0;
 
		while(u != r){
			ll mx = 0;
			for(int e : g[u])
				if(e != r && v != p[u] && v != last) mx = max(mx, s[v] - d[u]);
			if(a[u][0] != p[u] && a[u][0] != last) mx = max(mx, s[a[u][0]] - d[u]);
 
			res = max(res, d[a[r][0]] - d[u] + mx + s[p[u]]);
			last = u;
			u = p[u];
		}
		res += a[r][1];
		ans += max(best, res);
	}
 
	cout << ans;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 23756 KB Output is correct
2 Correct 14 ms 23844 KB Output is correct
3 Correct 14 ms 23800 KB Output is correct
4 Correct 14 ms 23824 KB Output is correct
5 Correct 14 ms 23824 KB Output is correct
6 Correct 13 ms 23700 KB Output is correct
7 Correct 17 ms 23756 KB Output is correct
8 Correct 13 ms 23756 KB Output is correct
9 Correct 13 ms 23796 KB Output is correct
10 Correct 14 ms 23772 KB Output is correct
11 Correct 14 ms 23792 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 23816 KB Output is correct
2 Correct 14 ms 23884 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 23924 KB Output is correct
2 Correct 16 ms 24140 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 25 ms 24604 KB Output is correct
2 Correct 33 ms 26564 KB Output is correct
3 Correct 24 ms 24780 KB Output is correct
4 Correct 19 ms 24328 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 37 ms 27632 KB Output is correct
2 Correct 57 ms 30064 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 98 ms 34500 KB Output is correct
2 Correct 115 ms 43148 KB Output is correct
3 Correct 127 ms 48124 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 154 ms 44612 KB Output is correct
2 Correct 209 ms 62904 KB Output is correct
3 Correct 252 ms 80028 KB Output is correct
4 Correct 307 ms 86616 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 334 ms 59308 KB Output is correct
2 Correct 896 ms 108524 KB Output is correct
3 Correct 292 ms 61808 KB Output is correct
4 Correct 404 ms 94796 KB Output is correct
5 Correct 399 ms 93012 KB Output is correct
6 Correct 1014 ms 69704 KB Output is correct
7 Correct 435 ms 120084 KB Output is correct

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 365 ms 131076 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -