Submission #1119635

#	Time	Username	Problem	Language	Result	Execution time	Memory
1119635		tradz	Valley (BOI19_valley)	C++14	100 / 100	148 ms	54188 KiB

valley

#include <bits/stdc++.h>
#define TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define For(i,a,b) for(int i = a; i <= b; i++)
#define Ford(i,a,b) for(int i = a; i >= b; i--)
#define ll long long
#define ii pair<int,int>
#define fi first
#define se second
#define all(v) v.begin(),v.end()
#define RRH(v) v.resize(unique(all(v)) - v.begin())

using namespace std;
const int  N = 1e6+7;
const int M = 1e9+7;
const ll oo = 3e18;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

long long GetRandom(long long l, long long r) {
    return uniform_int_distribution<long long> (l, r)(rng);
}

int n, s, q, e, timedfs = 0, tin[N], tout[N], h[N];
vector <ii> g[N];
ll d[N];

bool isAnc(int u, int v) {
    return (tin[u] >= tin[v] && tin[u] <= tout[v]);
}

int sz[N], head[N], depth[N], big[N], par[N];

void DFS(int u) {
    sz[u] = 1;
    big[u] = 0;
    for (auto [v, w]: g[u]) {
        if (v == par[u]) continue;
        par[v] = u;
        d[v] = d[u] + w;
        depth[v] = depth[u] + 1;
        DFS(v);
        if (sz[v] > sz[big[u]]) big[u] = v;
        sz[u] += sz[v];
    }
}

void HLD(int u) {
    tin[u] = ++timedfs;
    if (big[u]) {
        head[big[u]] = head[u];
        h[big[u]] = h[u];
        HLD(big[u]);
    }
    
    for (auto [v, w]: g[u]) {
        if (v == par[u] || v == big[u]) continue;
        h[v] = h[u] + 1;
        head[v] = v;
        HLD(v);
    }
    tout[u] = timedfs;
}

int spe[N];
bool spec[N];
ll dist[N];
void dfs(int u) {
    dist[u] = oo;
    if (spec[u]) {
        dist[u] = d[u];
    }
    for (auto [v, w]: g[u]) {
        if (v == par[u]) continue;
        dfs(v);
        dist[u] = min(dist[u], dist[v]);
    }
}

pair <int, int> ed[N];
ll ma[20][N];

ll get(int l, int r) {
    int k = log2(r - l + 1);
    return min(ma[k][l], ma[k][r - (1 << k) + 1]);
}

ll query(int u, int v) {
    ll ans = oo;
    for (;head[u] != head[v]; u = par[head[u]]) {
        if (h[u] < h[v]) swap(u, v);
        ans = min(ans, get(tin[head[u]], tin[u]));
    }
    
    if (tin[u] > tin[v]) swap(u, v);
    ans = min(ans, get(tin[u], tin[v]));
    return ans;
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);

    #define TASK ""
    if (fopen (".inp", "r")) {
        freopen (".inp", "r", stdin);
        freopen (".out", "w", stdout);
    }
    if(fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    
    cin >> n >> s >> q >> e;
    
    For (i, 1, n - 1) {
        int u, v, w; cin >> u >> v >> w;
        ed[i] = {u, v};
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    
    depth[e] = 0;
    d[e] = 0;
    DFS(e);
    h[e] = 1;
    head[e] = e;
    HLD(e);
    for (int i = 1; i <= s; i++) {
        cin >> spe[i];
        spec[spe[i]] = 1;
    }
    dfs(e);
    for (int i = 1; i < n; i++) {
        if (tin[ed[i].fi] > tin[ed[i].se]) swap(ed[i].fi, ed[i].se);
    }
    
    for (int i = 1; i <= n; i++) {
        ma[0][tin[i]] = dist[i] - 2ll * d[i];
    }
    
    for (int j = 1; (1 << j) <= n; j++) {
        for (int i = 1; i <= n - (1 << j) + 1; i++) {
            ma[j][i] = min(ma[j - 1][i], ma[j - 1][i + (1 << j - 1)]);
        }
    }

    while (q--) {
        int id, r; cin >> id >> r;
        int v = ed[id].se;
        if (!isAnc(r, v)) {
            cout << "escaped\n";
            continue;
        }
        if (dist[v] == oo) {
            cout << "oo\n";
            continue;
        }
        cout << d[r] + query(r, v) << '\n';
    }
    

    cerr << "Time elapsed: " << TIME << " s.\n";
    return 0;
}

Compilation message (stderr)

valley.cpp: In function 'void DFS(int)':
valley.cpp:36:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   36 |     for (auto [v, w]: g[u]) {
      |               ^
valley.cpp: In function 'void HLD(int)':
valley.cpp:55:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   55 |     for (auto [v, w]: g[u]) {
      |               ^
valley.cpp: In function 'void dfs(int)':
valley.cpp:72:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   72 |     for (auto [v, w]: g[u]) {
      |               ^
valley.cpp: In function 'int main()':
valley.cpp:142:64: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
  142 |             ma[j][i] = min(ma[j - 1][i], ma[j - 1][i + (1 << j - 1)]);
      |                                                              ~~^~~
valley.cpp:104:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  104 |         freopen (".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~
valley.cpp:105:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  105 |         freopen (".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
valley.cpp:108:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:109:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  109 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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