Submission #1116644

#	Time	Username	Problem	Language	Result	Execution time	Memory
1116644		gdragon	Valley (BOI19_valley)	C++17	59 / 100	3036 ms	19784 KiB

valley

#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 1e5 + 5;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
struct Fenwick {
    int n;
    vector<long long> v;
    Fenwick(int _n = 0) {
        n = _n;
        v.assign(n + 2, 0);
    }
    void update(int x, int c) {
        for(; x <= n; x += x & -x) v[x] += c;
    }
    long long get(int x) {
        long long ans = 0;
        for(; x > 0; x -= x & -x) ans += v[x];
        return ans;
    }
    long long get(int l, int r) {
        return (get(r) - get(l - 1));
    }
} fw, weight;
int n, q, numShop, root;
int tin[N], tout[N], high[N], head[N], sz[N], par[N];
pair<int, int> e[N];
vector<pair<int, int>> adj[N];
vector<int> shops;
void read() {
    cin >> n >> numShop >> q >> root;
    for(int i = 1; i < n; i++) {
        int u, v, c; cin >> u >> v >> c;
        adj[u].push_back({v, c});
        adj[v].push_back({u, c});
        e[i] = {u, v};
    }
    shops.resize(numShop);
    for(auto&i : shops) cin >> i;
}
int timer = 0;
void dfs(int u, int p) {
    sz[u] = 1;
    par[u] = p;
    for(auto& i: adj[u]) {
        int v = i.fi;
        if (v == p) continue;
        high[v] = high[u] + 1;
        dfs(v, u);
        sz[u] += sz[v];
    }
}
bool isChild(int u, int p) {
    return tin[u] >= tin[p] && tin[u] <= tout[p];
}
void hld(int u, int p, int top, int w) {
    tin[u] = ++timer;
    head[u] = top;
    // cerr << u << ' ' << head[u] << endl;
    if (p != -1) weight.update(tin[u], w);
    int bigC = -1, bigW = -1;
    for(auto &i: adj[u]) {
        int v = i.fi;
        if (v == p) continue;
        if (bigC == -1 || sz[bigC] < sz[v]) {
            bigC = v;
            bigW = i.se;
        }
    }
    if (bigC == -1) {
        tout[u] = timer;
        return;
    }
    hld(bigC, u, top, bigW);
    for(auto &i: adj[u]) {
        int v = i.fi;
        if (v == p || v == bigC) continue;
        hld(v, u, v, i.se);
    }
    tout[u] = timer;
}
long long get(int u, int v) {
    // if (high[u] < high[v]) swap(u, v);
    long long ans = 0;
    // cerr << "DB: " << u << ' ' << v << endl;
    while(head[u] != head[v]) {
        if (high[head[u]] < high[head[v]]) swap(u, v);
        ans += weight.get(tin[head[u]], tin[u]);
        // cerr << head[u] << ' ' << u << endl;
        u = par[head[u]]; 
    }
    if (high[u] > high[v]) swap(u, v);
    ans += weight.get(tin[u] + 1, tin[v]);
    return ans;
}
void sub1() {
    fw = Fenwick(n);
    weight = Fenwick(n);
    dfs(root, -1);
    hld(root, -1, root, 0);
    for(int shop: shops) fw.update(tin[shop], 1);
    while(q--) {
        int road, node; cin >> road >> node;
        int u = e[road].fi, v = e[road].se;
        if (high[u] > high[v]) swap(u, v);
        if (isChild(node, v)) {
            if (fw.get(tin[v], tout[v]) == 0) {
                cout << "oo\n";
                continue;
            }
            if (numShop == n) {
                cout << 0 << endl;
                continue;
            }
            long long ans = INF;
            for(int shop: shops) if (isChild(shop, v)) {
                ans = min(ans, get(shop, node));
            }
            cout << ans << endl;
        }
        else cout << "escaped\n";
    }
}
void solve() {
    sub1();
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    int test = 1;
    // cin >> test;
    while(test--) {
        read();
        solve();
    }
    return 0;
}

Compilation message (stderr)

valley.cpp: In function 'int main()':
valley.cpp:144:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  144 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:145:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  145 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 23 / 23
• Subtask 4: 0 / 41