Submission #1096338

#	Time	Username	Problem	Language	Result	Execution time	Memory
1096338		TrieTr	Valley (BOI19_valley)	C++14	100 / 100	140 ms	55244 KiB

valley

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

void local() {
	#define taskname ""
	if(fopen(taskname".inp", "r")) {
		freopen(taskname".inp", "r", stdin);
		freopen(taskname".out", "w", stdout);
	}
}

#define ll long long
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

template <class X, class Y> bool mini(X& x, Y y) {return x > y ? x = y, true : false;}
template <class X, class Y> bool maxi(X& x, Y y) {return x < y ? x = y, true : false;}

const int N = 1e5 + 5;
const int LG = 17;

int n, s, q, h, c[N];
vector<tuple<int, int, int>>edge;
pair<int, int>query[N];

namespace sub2 {
	bool check() {
		return n * q <= 1e6;
	}
	vector<pair<int, int>>adj[N];
	bitset<N>flag;
	ll res = 1e18;
	void dfs(int u, int p, ll d) {
		if(u == h) res = -1;
		if(flag[u]) mini(res, d);
		for(pair<int, int>& pi : adj[u]) {
			int v, w; tie(v, w) = pi;
			if(v == p) continue;
			dfs(v, u, d + w);
		}
	}
	void solve() {
		for(int i = 1; i <= s; i++) flag[c[i]] = true;
		for(int _ = 1; _ <= q; _++) {
			int ban, r; tie(ban, r) = query[_];
			for(int i = 1; i <= n; i++) adj[i].clear();
			for(int i = 1; i < n; i++) {
				if(i == ban) continue;
				int u, v, w; tie(u, v, w) = edge[i];
				adj[u].emplace_back(v, w); adj[v].emplace_back(u, w);
			}
			res = 1e18; dfs(r, 0, 0);
			if(res == -1) cout << "escaped\n";
			else if(res < 1e18) cout << res << '\n';
			else cout << "oo\n";
		}
	}
}

namespace sub3 {
	bool check() {
		return s == n;
	}
	bool res[N];
	vector<int>adj[N];
	int st[N], en[N], id = 0;
	void pre_dfs(int u, int p) {
		st[u] = ++id;
		for(int& v: adj[u]) {
			if(v == p) continue;
			pre_dfs(v, u);
		}
		en[u] = id;
	}
	bool isin(int x, int l, int r) {
		return l <= x && x <= r;
	}
	void solve() {
		for(int i = 1; i < n; i++) {
			int u, v, w; tie(u, v, w) = edge[i];
			adj[u].emplace_back(v); adj[v].emplace_back(u);
		}
		pre_dfs(h, 0);
		for(int i = 1; i <= q; i++) {
			int ban, r; tie(ban, r) = query[i];
			int u, v, w; tie(u, v, w) = edge[ban];
			if(st[u] > st[v]) swap(u, v);
			if(isin(st[r], st[v], en[v])) cout << "0\n";
			else cout << "escaped\n";
		}
	}
}

namespace sub4 {
	bitset<N>flag;
	ll res[N];
	vector<pair<int, int>>adj[N];
	vector<pair<int, int>>event[N];
	int st[N], en[N], id = 0, de[N]; ll mi[N], dist[N], up[N][LG], e[N][LG], upw[N];
	void pre_dfs(int u, int p) {
		st[u] = ++id;
		mi[u] = 1e18;
		for(pair<int, int>& pi : adj[u]) {
			int v, w; tie(v, w) = pi;
			if(v == p) continue;
			upw[v] = w;
			dist[v] = dist[u] + w;
			de[v] = de[up[v][0] = u] + 1;
			for(int i = 1; (1 << i) <= de[v]; i++) up[v][i] = up[up[v][i - 1]][i - 1];
			pre_dfs(v, u);
			mini(mi[u], mi[v] + w);
		}
		en[u] = id;
		if(flag[u]) mi[u] = 0;
	}
	void dfs1(int u, int p) {
		pair<ll, int> p0, p1;
		p0 = p1 = make_pair(1e18, 0), make_pair(1e18, 0);
		for(pair<int, int>& pi : adj[u]) {
			int v, w; tie(v, w) = pi;
			if(v == p) continue;
			dfs1(v, u);
			if(flag[u]) e[v][0] = w;
			if(!mini(p0, make_pair(mi[v] + w, v))) mini(p1, make_pair(mi[v] + w, v));
		}
		for(pair<int, int>& pi : adj[u]) {
			int v, w; tie(v, w) = pi;
			if(v == p) continue;
			if(p0.se == v) mini(e[v][0], p1.fi + upw[v]);
			else mini(e[v][0], p0.fi + upw[v]);
			//cout << v << ' ' << e[v][0] << '\n';
		}
	}
	void dfs2(int u, int p) {
		for(int i = 1; (1 << i) <= de[u]; i++) {
			e[u][i] = min(e[u][i - 1], e[up[u][i - 1]][i - 1] + dist[u] - dist[up[u][i - 1]]);
			//cout << u << ' ' << i << ' ' << up[u][i - 1] << ' ' << e[up[u][i - 1]][i - 1] << ' ' << dist[u] - dist[up[u][i - 1]] << ' ' << e[u][i] << '\n';
		}
		for(pair<int, int>& pi : adj[u]) {
			int v, w; tie(v, w) = pi;
			if(v == p) continue;
			dfs2(v, u);
		}
	}
	bool isin(int x, int l, int r) {
		return l <= x && x <= r;
	}
	void solve() {
		for(int i = 1; i <= s; i++) flag[c[i]] = true;
		for(int i = 1; i < n; i++) {
			int u, v, w; tie(u, v, w) = edge[i];
			adj[u].emplace_back(v, w); adj[v].emplace_back(u, w);
		}
		for(int i = 1; i <= n; i++) {
			for(int j = 0; j < LG; j++) {
				e[i][j] = 1e18;
			}
		}
		pre_dfs(h, 0);
		dfs1(h, 0); dfs2(h, 0);
		e[h][0] = mi[h];
		for(int i = 1; i <= q; i++) {
			res[i] = 1e18;
			int ban, r; tie(ban, r) = query[i];
			int u, v, w; tie(u, v, w) = edge[ban];
			if(st[u] > st[v]) swap(u, v);
			if(!isin(st[r], st[v], en[v])) cout << "escaped\n";
			else {
				res[i] = mi[r];
				int dst = de[r] - de[v], u = r;
				for(int j = 0; (1 << j) <= dst; j++) {
					if(dst & (1 << j)) {
						mini(res[i], e[u][j] + dist[r] - dist[u]);
						u = up[u][j];
					}
				}
				if(res[i] >= 1e18) cout << "oo\n";
				else cout << res[i] << '\n';
			}
		}
	}
}

int main() {
	fastio; local();
	cin >> n >> s >> q >> h;
	edge.emplace_back(0, 0, 0);
	for(int i = 1; i < n; i++) {
		int u, v, w ; cin >> u >> v >> w;
		edge.emplace_back(u, v, w);
	}
	for(int i = 1; i <= s; i++) cin >> c[i];
	for(int i = 1; i <= q; i++) cin >> query[i].fi >> query[i].se;

	sub4::solve();
}

Compilation message (stderr)

valley.cpp: In function 'void local()':
valley.cpp:7:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    7 |   freopen(taskname".inp", "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:8:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 |   freopen(taskname".out", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 23 / 23
• Subtask 4: 41 / 41