Submission #850996

#	Time	Username	Problem	Language	Result	Execution time	Memory
850996		iah	Harbingers (CEOI09_harbingers)	C++14	100 / 100	80 ms	21924 KiB

harbingers

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

#define ll long long
#define ii pair < int , int >
#define il pair < int , ll >
#define fi first
#define se second
constexpr int Nmax = 1e5 + 5;
ll f[Nmax], v[Nmax], d[Nmax], s[Nmax];
vector < il > adj[Nmax];
struct line {
	ll a, b;
	ll calc(ll x) {
		return a * x + b;
	}
	double intersect(line x) {
		return (double)(x.b - b) / (double)(a - x.a);
	}
}a[Nmax];

struct ope {
	int id, old_top;
	line old_id;
};
stack < ope > st;
int top = 0;

void add(line x) {
	
	int l = 2, r = top, ans = top + 1;
	while (l <= r) {
		int mid = (l + r) / 2;
		if (a[mid - 1].intersect(x) <= a[mid - 1].intersect(a[mid])) {
			ans = mid;
			r = mid - 1;
		}
		else l = mid + 1;
	}
	
	st.push({ans, top, a[ans]});
	top = ans;
	a[ans] = x;
}

void undo() {
	auto t = st.top();
	st.pop();
	top = t.old_top;
	a[t.id] = t.old_id;
}

ll query(ll x) {
	
	int l = 2, r = top, ans = 1;
	while (l <= r) {
		int mid = (l + r) / 2;
		if (a[mid - 1].intersect(a[mid]) <= x) {
			ans = mid;
			l = mid + 1;
		}
		else r = mid - 1;
	}
	return a[ans].calc(x);
}

void dfs(int i, int j) {
	if (i != 1) {
		f[i] = query(v[i]) + s[i] + v[i] * d[i];
	}
	add(line{-d[i], f[i]});
	for (auto x:adj[i]) {
		int u = x.fi, w= x.se;
		if (u == j) continue;
		d[u] = d[i] + w;
		dfs(u, i);
	}
	undo();
}
signed main() {
    if (fopen(".inp","r")) {
        freopen(".inp","r",stdin);
        freopen(".out","w",stdout);
    }
    cin.tie(0)->sync_with_stdio(0);
    int n;
    cin >> n;
    for (int i = 1; i < n; i++) {
    	int u, v;
    	ll w;	
    	cin >> u >> v >> w;
    	adj[u].push_back({v, w});
    	adj[v].push_back({u, w});
    } 
    for (int i = 2; i <= n; i++) {
    	cin >> s[i] >> v[i];
    }
    dfs(1, 0);
    for (int i = 2; i <= n; i++) {
    	cout << f[i] << " ";
    }
    return 0;
}

Compilation message (stderr)

harbingers.cpp: In function 'int main()':
harbingers.cpp:82:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |         freopen(".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~
harbingers.cpp:83:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |         freopen(".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100