Submission #792718

#	Time	Username	Problem	Language	Result	Execution time	Memory
792718		IvanJ	Fireworks (APIO16_fireworks)	C++17	7 / 100	5 ms	7380 KiB

fireworks

#include<bits/stdc++.h>

#define pb push_back
#define x first
#define y second
#define all(a) (a).begin(), (a).end()

using namespace std;

typedef long long ll;
typedef pair<int, int> ii;

const int maxn = 3e5 + 5;

struct Data {
	int idx;
	ll lo, hi, ans;
};

int n, m;
ll depth[maxn];
Data dp[maxn];
vector<pair<int, ll>> adj[maxn];

void dfs(int x) {
	for(auto p : adj[x]) 
		depth[p.x] = p.y + depth[x], dfs(p.x);
}

Data solve(int x) {
	if(adj[x].size() == 0)
		return dp[x] = {x, depth[x], depth[x], 0};
	
	vector<Data> ch;
	for(auto p : adj[x]) 
		ch.pb(solve(p.x));
	
	int sz = 0;
	ll sum_l = 0, sum_r = 0;
	int cnt_l = 0, cnt_r = 0;
	for(Data D : ch) 
		sum_r += D.lo, sz++, cnt_r++;
	
	map<ll, vector<int>> L, R;
	set<ll> vals;
	ll sum = 0;
	for(Data D : ch) {
		sum += D.ans;
		L[D.lo].pb(D.idx);
		R[D.hi].pb(D.idx);
		vals.insert(D.lo), vals.insert(D.hi);
	}
	
	vector<ll> v;
	ll ans = 1e18;
	for(ll val : vals) {
		for(int y : L[val]) 
			sum_r -= dp[y].lo, cnt_r--;
		
		ll ansi = sum_r - sum_l + (ll)(cnt_l - cnt_r) * val;
		if(abs(cnt_r - cnt_l) <= sz - cnt_r - cnt_l) {
			if(ansi < ans) v.clear(), ans = ansi;
			if(ansi == ans) v.pb(val);
		}
		
		for(int y : R[val]) 
			sum_l += dp[y].hi, cnt_l++;
	}
	
	Data ret;
	ret.idx = x;
	ret.ans = ans + sum;
	ret.lo = v[0];
	ret.hi = v.back();
	//cout << x + 1 << " -> " << ret.lo << " " << ret.hi << " " << ret.ans << "\n";
	return dp[x] = ret;
}

int main() {
	scanf("%d%d", &n, &m);
	for(int i = 1;i < n + m;i++) {
		int p, c;
		scanf("%d%d", &p, &c);
		p--;
		adj[p].pb({i, c});
	}
	dfs(0);
	Data ans = solve(0);
	printf("%lld\n", ans.ans);
	return 0;
}

Compilation message (stderr)

fireworks.cpp: In function 'int main()':
fireworks.cpp:80:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
fireworks.cpp:83:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |   scanf("%d%d", &p, &c);
      |   ~~~~~^~~~~~~~~~~~~~~~

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