Submission #496470

#	Time	Username	Problem	Language	Result	Execution time	Memory
496470		Ziel	Valley (BOI19_valley)	C++17	100 / 100	496 ms	54300 KiB

valley

/**
 * LES GREATEABLES BRO TEAM
**/

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
#define sz(x) (int)x.size()
const bool FLAG = false;
void setIO(const string &f = "");

string to_string(const string s) {
	return '"' + s + '"';
}
string to_string(const char c) {
 	return char(39) + string(1, c) + char(39);
}
string to_string(const char* s) {
 	return to_string(string(s));
}
string to_string(bool f) {
	return (f ? "true" : "false");
}
template<class A, class B>
string to_string(const pair<A, B> x) {
	return "(" + to_string(x.first) + ", " + to_string(x.second) + ")";
}
template<class A, class B, class C>
string to_string(const tuple<A, B, C> x) {
	return "(" + to_string(get<0>(x)) + ", " + to_string(get<1>(x)) + ", " + to_string(get<2>(x)) + ")";
}
template<class A, class B, class C, class D>
string to_string(const tuple<A, B, C, D> x) {
	return "(" + to_string(get<0>(x)) + ", " + to_string(get<1>(x)) + ", " + to_string(get<2>(x)) + ", " + to_string(get<3>(x)) + ")";
}
template<class T>
string to_string(const T v) {
	string res = "{"; bool f = true;
	for (auto x: v)
		res += (f ? to_string(x) : ", " + to_string(x)), f = false;
	return res + "}";
}
void debug_args() { cerr << "]\n"; }
template<class H, class... T>
void debug_args(H x, T... y) {
	cerr << to_string(x);
	if (sizeof... (y))
	cerr << ", ";
	debug_args(y...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]: [", debug_args(__VA_ARGS__);
#else
#define debug(...) 47
#endif

#define int ll

const int N = 2e5 + 13, INF = 1e18 + 14;

int level[N], up[20][N], dist[N], dp[N], mn[20][N];
set<int> shop;
vector<vector<pair<int, int>>> g(N);

void dfs(int v, int pr, int d = 0) {
	up[0][v] = pr;
	level[v] = level[pr] + 1;
	dist[v] = dist[pr] + d;

	for (int i = 1; i <= 18; i++)
		up[i][v] = up[i - 1][up[i - 1][v]];
	dp[v] = INF + INF;
	if (shop.count(v))
		dp[v] = 0;
	for (auto [to, len]: g[v]) {
		if (to == pr)
			continue;
		dfs(to, v, len);
		dp[v] = min(dp[v], dp[to] + len);
	}
}
int lca(int x, int y) {
	if (level[x] > level[y])
		swap(x, y);
	for (int i = 18; i >= 0; i--) {
		if (level[up[i][y]] >= level[x])
			y = up[i][y];
	}
	if (x == y)
		return x;
	for (int i = 18; i >= 0; i--) {
		if (up[i][x] != up[i][y]) {
			x = up[i][x];
			y = up[i][y];
		}
	}
	return up[0][x];
}

void solve() {
    int n, s, q, e;
    cin >> n >> s >> q >> e;
    vector<pair<int, int>> edges(n);
    for (int i = 1; i < n; i++) {
    	int x, y, z;
    	cin >> x >> y >> z;
    	g[x].push_back({y, z});
    	g[y].push_back({x, z});
    	edges[i] = {x, y};
    }

    vector<int> c(s + 1);
    for (int i = 1; i <= s; i++) {
    	cin >> c[i];
    	shop.insert(c[i]);
    }
    dfs(e, 0);
    for (int j = 0; j <= 18; j++) {
    	for (int v = 1; v <= n; v++) {
    		if (!j)
    			mn[j][v] = dp[v] - dist[v];
    		else
    			mn[j][v] = min(mn[j - 1][v], mn[j - 1][up[j - 1][v]]);
    	}
    }
    
    while (q--) {
    	int edge, v;
    	cin >> edge >> v;
    	int x = edges[edge].first, y = edges[edge].second;

    	if (level[x] > level[y])
    		swap(x, y);
    	if (lca(y, v) == y) {
    		int res = INF;
    		int _v = v;
    		for (int i = 18; i >= 0; i--) {
    			if (level[up[i][v]] >= level[y]) {
    				res = min(res, mn[i][v]);
    				v = up[i][v];
    			}
    		}
    		res = min(res, dp[y] - dist[y]);
    		if (res >= INF)
    			cout << "oo\n";
    		else
	    		cout << dist[_v] + res << '\n';
    	} else {
    		cout << "escaped\n";
    	}
    }
}

signed main() {
    setIO();
    
    int tt = 1;
    if (FLAG) {
    	cin >> tt;
    }
    while (tt--) {
    	solve();
    }
    
    return 0;
}

void setIO(const string &f) {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (fopen((f + ".in").c_str(), "r")) {
        freopen((f + ".in").c_str(), "r", stdin);
        freopen((f + ".out").c_str(), "w", stdout);
    }
}

Compilation message (stderr)

valley.cpp: In function 'void setIO(const string&)':
valley.cpp:175:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  175 |         freopen((f + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:176:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  176 |         freopen((f + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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