Submission #36357

#	Time	Username	Problem	Language	Result	Execution time	Memory
36357		cheater2k	Fireworks (APIO16_fireworks)	C++14	7 / 100	6 ms	18580 KiB

fireworks

#include <bits/stdc++.h>
using namespace std;

const int N = 300010;
const long long inf = 1e18;

int n, m;
vector< pair<int,int> > G[N];
long long dp[N], tmp[N], dist[N];
int tin[N], tout[N], TIME;

// leaf: n + 1 -> n + m

bool inside(int fixed, int u) {
	return (tin[fixed] >= tin[u] && tin[fixed] <= tout[u]);
}

void dfs(int u) {
	tin[u] = ++TIME;
	for (auto e : G[u]) {
		int v = e.second, c = e.first;
		dist[v] = dist[u] + c;
		dfs(v);
	}
	tout[u] = TIME;
}

void solve(int u) {
	for (auto e : G[u]) {
		int v = e.second, c = e.first;
		solve(v);
	}

	for (int fixed = n + 1; fixed <= n + m; ++fixed) tmp[fixed] = 0;
	for (int fixed = n + 1; fixed <= n + m; ++fixed) {
		if (!inside(fixed, u)) continue;
		for (auto e : G[u]) {
			int v = e.second;
			long long mn = inf;
			for (int leaf = n + 1; leaf <= n + m; ++leaf) {
				if (!inside(leaf, v)) continue;
				long long cur = dp[leaf] + abs(dist[leaf] - dist[fixed]);
				mn = min(mn, cur);
			}
			tmp[fixed] += mn;
		}
	}
	for (int fixed = n + 1; fixed <= n + m; ++fixed) {
		if (inside(fixed, u)) dp[fixed] = tmp[fixed];
	}
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	cin >> n >> m;
	int nNode = n + m;
	for (int i = 2; i <= nNode; ++i) {
		int p, c; cin >> p >> c;
		G[p].push_back(make_pair(c, i));
	}
	dfs(1);
	solve(1);
	long long ans = inf;
	for (int fixed = n + 1; fixed <= n + m; ++fixed) {
		ans = min(ans, dp[fixed]);
	}
	cout << ans << endl;
}

Compilation message (stderr)

fireworks.cpp: In function 'void solve(int)':
fireworks.cpp:30:21: warning: unused variable 'c' [-Wunused-variable]
   int v = e.second, c = e.first;
                     ^

• Subtask 1: 7 / 7
• Subtask 2: 0 / 19
• Subtask 3: 0 / 29
• Subtask 4: 0 / 45