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Submission #439982

# Submission time Handle Problem Language Result Execution time Memory
439982 2021-07-01T10:33:24 Z dutch Islands (IOI08_islands) C++17
25 / 100
 674 ms 131076 KB 
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const int LIM = 1e6;

vector<array<int, 2>> a(LIM), g[LIM];
int r, p[LIM], dfsTimer, t0[LIM], t1[LIM];
ll best, d[LIM], s[LIM], pre[2*LIM], suf[2*LIM];
bitset<LIM> vis;

void dfs(int u, int par){
	s[u] = d[u], p[u] = par;
	t0[u] = dfsTimer++;
	ll curr = 0;
	for(auto &[v, w] : g[u]) if(v != par && v != r){
		d[v] = d[u] + (ll)w, dfs(v, u);
		s[u] = max(s[u], s[v]);
		best = max(best, curr + s[v] - d[u]);
		curr = max(curr, s[v] - d[u]);
	}
	t1[u] = dfsTimer++;
	pre[t0[u]] = suf[t0[u]] = d[u];
	pre[t1[u]] = suf[t1[u]] = 0;
}

void findCycle(int u, int par){
	vis[u] = 1;
	for(auto &[v, w] : g[u]) if(v != par){
		if(vis[v]) return void(r = v);
		findCycle(v, u);
		if(r >= 0) return;
	}
	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];
		g[--a[i][0]].push_back({i, a[i][1]});
	}
	fill(p, p+n, -1);

	ll ans = 0;

	for(int z=0; z<n; ++z){
		if(p[z] >= 0) continue;
		r = -1, best = 0;
		findCycle(z, z);
		bool cycle = r >= 0;
		if(!cycle) r = z;

		dfsTimer = 0;
		dfs(r, r);

		if(!cycle){
			ans += best;
			continue;
		}

		for(int i=1; i<dfsTimer; ++i) pre[i] = max(pre[i], pre[i-1]);
		for(int i=dfsTimer-2; i>=0; --i) suf[i] = max(suf[i], suf[i+1]);

		int u = a[r][0], last = -1;
		ll res = 0;
		while(u != r){
			ll mx = 0;
			for(auto &[v, w] : g[u])
				if(v != last) mx = max(mx, s[v] - d[u]);

			ll ex = 0;

			if(t0[u]) ex = max(ex, pre[t0[u]-1]);
			if(t1[u] + 1 < dfsTimer) ex = max(ex, suf[t1[u]+1]);

			res = max(res, d[a[r][0]] - d[u] + mx + ex);
			last = u;
			u = p[u];
		}
		res += a[r][1];

		ans += max(best, res);
	}

	cout << ans;
}

Subtask #1
15.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 31692 KB Output is correct
2 Incorrect 23 ms 31612 KB Output isn't correct
3 Correct 21 ms 31688 KB Output is correct
4 Correct 22 ms 31580 KB Output is correct
5 Correct 22 ms 31640 KB Output is correct
6 Incorrect 20 ms 31644 KB Output isn't correct
7 Incorrect 22 ms 31684 KB Output isn't correct
8 Incorrect 22 ms 31692 KB Output isn't correct
9 Incorrect 21 ms 31632 KB Output isn't correct
10 Correct 23 ms 31692 KB Output is correct
11 Incorrect 25 ms 31632 KB Output isn't correct

Subtask #2
0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 31820 KB Output is correct
2 Incorrect 25 ms 31740 KB Output isn't correct

Subtask #3
0 / 4.0

# Verdict Execution time Memory Grader output
1 Incorrect 22 ms 31820 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 30 ms 32828 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 51 ms 37328 KB Output is correct
2 Correct 60 ms 39688 KB Output is correct

Subtask #6
0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 113 ms 49172 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #7
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 157 ms 53700 KB Output is correct
2 Incorrect 232 ms 85440 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 384 ms 98748 KB Output is correct
2 Runtime error 674 ms 131076 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 426 ms 131076 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -