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답안 #439993

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
439993 2021-07-01T11:13:15 Z dutch Islands (IOI08_islands) C++17
6 / 100
 2000 ms 131072 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;
	}
}

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;
	int cnt = 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;
		}else ++cnt;

		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);
	}
	assert(cnt == 1);

	cout << ans;
}

Subtask #1
6.0 / 33.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 31692 KB Output is correct
2 Execution timed out 2079 ms 31676 KB Time limit exceeded
3 Correct 20 ms 31664 KB Output is correct
4 Runtime error 58 ms 63980 KB Execution killed with signal 6
5 Runtime error 61 ms 63980 KB Execution killed with signal 6
6 Execution timed out 2085 ms 31692 KB Time limit exceeded
7 Execution timed out 2084 ms 31692 KB Time limit exceeded
8 Execution timed out 2091 ms 31692 KB Time limit exceeded
9 Execution timed out 2095 ms 31692 KB Time limit exceeded
10 Runtime error 54 ms 64076 KB Execution killed with signal 6
11 Runtime error 57 ms 64100 KB Execution killed with signal 6

Subtask #2
0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 2085 ms 31696 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 2083 ms 31768 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #4
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 2089 ms 32588 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #5
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 2094 ms 33740 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #6
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 2096 ms 36420 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #7
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 217 ms 108152 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 481 ms 131072 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Execution timed out 2100 ms 130116 KB Time limit exceeded
2 Halted 0 ms 0 KB -