Submission #1095813

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095813		natus26	Valley (BOI19_valley)	C++17	36 / 100	66 ms	65104 KiB

valley

#include <bits/stdc++.h>
#define task "1"
#define ll long long
#define double long double
#define ii pair<int, int>
#define li pair<ll, int>
#define fi first
#define se second
#define all(v)         (v).begin(), (v).end()
#define FULL(i)        ((1LL << i) - 1)
#define MASK(i)        (1LL << i)
#define c_bit(i)       __builtin_popcountll(i)
#define Bit(mask, i)    ((mask >> i) & 1)
#define onbit(mask, i)  ((mask) bitor (1LL << i))
#define offbit(mask, i) ((mask) &~ (1LL << i))
using namespace std;
const int maxn = 1e5 + 5;
const ll oo = 1e16;
const int mod = 1e9 + 7;
const int dx[] = {0, 1, 0, -1} , dy[] = {1, 0, -1, 0};

template <class X, class Y> bool maximize(X &a, const Y &b)
{
    if(a < b) return a = b, true;
    return false;
}

template <class X, class Y> bool minimize(X &a, const Y &b)
{
    if(a > b) return a = b, true;
    return false;
}

int n, s, q, h, in[maxn], out[maxn], depth[maxn], pos[maxn]; ll res[maxn], t[maxn << 2]; bool shop[maxn];
vector<ii> adj[maxn]; vector<ii> queries[maxn]; ll d[maxn], lazy[maxn << 2]; ii rmq[maxn][20], edges[maxn];

void dfs(int u, int p)
{
    static int timeDfs = 0, id = 0;
    in[u] = ++ timeDfs;
    rmq[++ id][0] = {depth[u], u};
    pos[u] = id;
    for(auto [v, w] : adj[u]) if(v != p){
        depth[v] = depth[u] + 1;
        d[v] = d[u] + w;
        dfs(v, u);
        rmq[++ id][0] = {depth[u], u};
    }
    out[u] = timeDfs;
}

bool inSubTree(int v, int u) { return in[u] <= in[v] && in[v] <= out[u]; }

ll dist(int u, int v)
{
    int l = pos[u], r = pos[v];
    if(l > r) swap(l, r);
    int h = __lg(r - l + 1);
    int lca = min(rmq[l][h], rmq[r - (1 << h) + 1][h]).se;
    return d[u] + d[v] - 2 * d[lca];
}

void down(int id)
{
    if(!lazy[id]) return;
    for(int i : {id << 1, id << 1 | 1}){
        t[i] += lazy[id];
        lazy[i] += lazy[id];
    }
    lazy[id] = 0;
}

void update(int u, int v, ll val, int id = 1, int l = 1, int r = n)
{
    if(r < u || l > v) return;
    if(u <= l && r <= v){
        t[id] += val;
        lazy[id] += val;
        return;
    }
    down(id);
    int mid = l + r >> 1;
    update(u, v, val, id << 1, l, mid);
    update(u, v, val, id << 1 | 1, mid + 1, r);
    t[id] = min(t[id << 1], t[id << 1 | 1]);
}

ll get(int u, int v, int id = 1, int l = 1, int r = n)
{
    if(r < u || l > v) return oo;
    if(u <= l && r <= v) return t[id];
    down(id);
    int mid = l + r >> 1;
    return min(get(u, v, id << 1, l, mid), get(u, v, id << 1 | 1, mid + 1, r));
}

void solve(int u, int p)
{
    for(auto [e, i] : queries[u]){
        auto [x, y] = edges[e];
        if(depth[x] < depth[y]) swap(x, y);
        if(!inSubTree(u, x)) { res[i] = -1; continue; }
        res[i] = get(in[x], out[x]);
    }
    for(auto [v, w] : adj[u]) if(v != p){
        update(in[v], out[v], -w);
        update(1, in[v] - 1, w);
        update(out[v] + 1, n, w);
        solve(v, u);
        update(in[v], out[v], w);
        update(1, in[v] - 1, -w);
        update(out[v] + 1, n, -w);
    }
}

int main()
{
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    cin >> n >> s >> q >> h;
    for(int i = 1; i < n; ++ i){
        int u, v, w; cin >> u >> v >> w;
        edges[i] = {u, v};
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }

    dfs(h, 0);

    for(int k = 1; 1 << k <= n << 1; ++ k) for(int i = 1; i + (1 << k) - 1 <= n << 1; ++ i)
        rmq[i][k] = min(rmq[i][k - 1], rmq[i + (1 << k - 1)][k - 1]);
    
    for(int i = 1; i <= s; ++ i){
        int u; cin >> u;
        shop[u] = true;
        update(in[u], in[u], dist(u, h));
    }
    
    for(int u = 1; u <= n; ++ u) if(!shop[u]) update(in[u], in[u], oo);

    for(int i = 1; i <= q; ++ i){
        int e, u; cin >> e >> u;
        queries[u].push_back({e, i});
    }

    solve(h, 0);

    for(int i = 1; i <= q; ++ i){
        if(!~res[i]) cout << "escaped\n";
        else if(res[i] > 1e14) cout << "oo\n";
        else cout << res[i] << '\n';
    }
    return 0;
}

Compilation message (stderr)

valley.cpp: In function 'void update(int, int, long long int, int, int, int)':
valley.cpp:82:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   82 |     int mid = l + r >> 1;
      |               ~~^~~
valley.cpp: In function 'long long int get(int, int, int, int, int)':
valley.cpp:93:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   93 |     int mid = l + r >> 1;
      |               ~~^~~
valley.cpp: In function 'int main()':
valley.cpp:134:56: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
  134 |         rmq[i][k] = min(rmq[i][k - 1], rmq[i + (1 << k - 1)][k - 1]);
      |                                                      ~~^~~
valley.cpp:120:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  120 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:121:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  121 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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