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Submission #83391

# Submission time Handle Problem Language Result Execution time Memory
83391 2018-11-07T13:40:59 Z Tusk Islands (IOI08_islands) C++14
80 / 100
 434 ms 132096 KB 
#include <bits/stdc++.h>

#define pll pair<long long, long long>
#define x first
#define y second

using namespace std;

const int N = 1e6 + 5;

int n;
long long deg[N], dm[N];
pll par[N], dp[N];
bitset<N> vis;

long long solve(int u) {
	long long ret = 0;
	int sz;
	vector<pll> V;
	deque<pll> Q;

	V.emplace_back(0, 0);
	while(deg[u]) {
		deg[u]--;
		dm[u] = max(dm[u], dp[u].x + dp[u].y);
		ret = max(ret, dm[u]);
		V.emplace_back(u, par[u].y);
		u = par[u].x;
	}

 	sz = V.size() - 1;
	for(int i = 1; i <= sz; i++) V[i].y += V[i - 1].y;
	for(int i = 2; i <= sz; i++) {
		while(!Q.empty() && Q.back().x < V[i - 1].y + dp[V[i].x].x) Q.pop_back();
		Q.emplace_back(V[i - 1].y + dp[V[i].x].x, i);
	}
	ret = max(ret, dp[V[1].x].x + Q.front().x);
	for(int i = 1; i < sz; i++) {
		if(Q.front().y == i + 1) Q.pop_front();
		while(!Q.empty() && Q.back().x < V[sz].y + V[i - 1].y + dp[V[i].x].x) Q.pop_back();
		Q.emplace_back(V[sz].y + V[i - 1].y + dp[V[i].x].x, i);
		ret = max(ret, dp[V[i + 1].x].x + Q.front().x - V[i].y);
	}

	return ret;
}

int main() {
	scanf("%d", &n);
	for(int i = 1, v, w; i <= n; i++) {
		scanf("%d %d", &v, &w);
		par[i] = pll(v, w);
		deg[v]++;
	}

	queue<int> Q;
	for(int i = 1; i <= n; i++) if(!deg[i]) Q.emplace(i);

	while(!Q.empty()) {
		int now = Q.front();
		Q.pop();

		long long p = par[now].x, w = par[now].y;
		dm[now] = max(dm[now], dp[now].x + dp[now].y);
		dm[p] = max(dm[p], dm[now]);

		long long ret = dp[now].x + w;
		if(ret > dp[p].x) swap(ret, dp[p].x);
		if(ret > dp[p].y) swap(ret, dp[p].y);
		if(!--deg[p]) Q.emplace(p);
	}

	long long ans = 0;
	for(int i = 1; i <= n; i++) if(deg[i]) ans += solve(i);

	printf("%lld", ans);

	return 0;
}

Compilation message

islands.cpp: In function 'int main()':
islands.cpp:49:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ~~~~~^~~~~~~~~~
islands.cpp:51:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &v, &w);
   ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 376 KB Output is correct
2 Correct 2 ms 504 KB Output is correct
3 Correct 2 ms 504 KB Output is correct
4 Correct 2 ms 612 KB Output is correct
5 Correct 2 ms 728 KB Output is correct
6 Correct 2 ms 740 KB Output is correct
7 Correct 2 ms 740 KB Output is correct
8 Correct 2 ms 752 KB Output is correct
9 Correct 2 ms 756 KB Output is correct
10 Correct 2 ms 756 KB Output is correct
11 Correct 2 ms 760 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 780 KB Output is correct
2 Correct 3 ms 808 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 972 KB Output is correct
2 Correct 5 ms 1140 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 1968 KB Output is correct
2 Correct 17 ms 3592 KB Output is correct
3 Correct 11 ms 3592 KB Output is correct
4 Correct 8 ms 3592 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 5696 KB Output is correct
2 Correct 38 ms 8888 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 90 ms 16660 KB Output is correct
2 Correct 97 ms 20368 KB Output is correct
3 Correct 101 ms 28516 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 161 ms 35692 KB Output is correct
2 Correct 183 ms 51828 KB Output is correct
3 Correct 181 ms 57136 KB Output is correct
4 Correct 234 ms 77240 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 319 ms 81364 KB Output is correct
2 Correct 434 ms 114600 KB Output is correct
3 Correct 296 ms 117224 KB Output is correct
4 Runtime error 380 ms 132096 KB Memory limit exceeded: We have a known bug that the memory usage is measured incorrectly (possibly because of Meltdown/Spectre patch), so your solution may be correct. Please submit again. Sorry for the inconvenience.
5 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 354 ms 132096 KB Memory limit exceeded: We have a known bug that the memory usage is measured incorrectly (possibly because of Meltdown/Spectre patch), so your solution may be correct. Please submit again. Sorry for the inconvenience.
2 Halted 0 ms 0 KB -