Submission #494307

#	Time	Username	Problem	Language	Result	Execution time	Memory
494307		wiwiho	Valley (BOI19_valley)	C++14	100 / 100	984 ms	118312 KiB

valley

#include <bits/stdc++.h>
#include <bits/extc++.h>

#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define ef(a) emplace_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define tomax(a, b) ((a) = max((a), (b)))
#define tomin(a, b) ((a) = min((a), (b)))
#define topos(a) ((a) = (((a) % MOD + MOD) % MOD))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
    if(pvaspace) b << " "; pvaspace=true;\
    b << pva;\
}\
b << "\n";}

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;

using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;

const ll MOD = 1000000007;
const ll MAX = 1LL << 60;

template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
    return o << '(' << p.F << ',' << p.S << ')';
}

ll ifloor(ll a, ll b){
    if(b < 0) a *= -1, b *= -1;
    if(a < 0) return (a - b + 1) / b;
    else return a / b;
}

ll iceil(ll a, ll b){
    if(b < 0) a *= -1, b *= -1;
    if(a > 0) return (a + b - 1) / b;
    else return a / b;
}

int n;
struct SegmentTree{
    vector<ll> st;
    int sz;
    explicit SegmentTree(int sz): sz(sz){
        st.resize(4 * sz, MAX);
    }
    void modify(int x, ll v, int L = 1, int R = n, int id = 0){
        //cerr << "modify " << x << " " << v << " " << L << " " << R << " " << sz << "\n";
        //assert(L <= R);
        if(L == R){
            st[id] = v;
            return;
        }
        int M = (L + R) / 2;
        if(x <= M) modify(x, v, L, M, 2 * id + 1);
        else modify(x, v, M + 1, R, 2 * id + 2);
        st[id] = min(st[2 * id + 1], st[2 * id + 2]);
    }
    ll query(int l, int r, int L = 1, int R = n, int id = 0){
        if(l > r) return MAX;
        if(l <= L && R <= r) return st[id];
        int M = (L + R) / 2;
        if(r <= M) return query(l, r, L, M, 2 * id + 1);
        else if(l > M) return query(l, r, M + 1, R, 2 * id + 2);
        else return min(query(l, r, L, M, 2 * id + 1), query(l, r, M + 1, R, 2 * id + 2));
    }
};


vector<vector<pii>> g;
vector<bool> shop;
vector<vector<int>> pr, in, out;
vector<vector<ll>> dpt;
vector<SegmentTree> st;
vector<int> sz, ts;
vector<bool> del;

const int SZ = 20;

vector<pii> e;
int esc;

void init(){
    g.resize(n + 1);
    shop.resize(n + 1);
    pr.resize(SZ, vector<int>(n + 1, -1));
    in.resize(SZ, vector<int>(n + 1, -1));
    out.resize(SZ, vector<int>(n + 1, -1));
    dpt.resize(SZ, vector<ll>(n + 1));
    st.resize(SZ, SegmentTree(n));
    sz.resize(n + 1);
    del.resize(n + 1);
    ts.resize(SZ);

    e.resize(n);
}

void dfsg(int now, int p){
    sz[now] = 1;
    for(pii i : g[now]){
        if(i.F == p || del[i.F]) continue;
        dfsg(i.F, now);
        sz[now] += sz[i.F];
    }
}

int cen;
void dfsg2(int now, int p, int t){
    int mx = t - sz[now];
    for(pii i : g[now]){
        if(i.F == p || del[i.F]) continue;
        mx = max(mx, sz[i.F]);
        dfsg2(i.F, now, t);
    }
    if(mx <= t / 2) cen = now;
}

void dfssub(int now, int p, ll d, int gd){
    in[gd][now] = ++ts[gd];
    pr[gd][now] = cen;
    dpt[gd][now] = d;
    if(shop[now]){
        st[gd].modify(in[gd][now], d, 1, n, 0);
    }
    for(pii i : g[now]){
        if(i.F == p || del[i.F]) continue;
        dfssub(i.F, now, d + i.S, gd);
    }
    out[gd][now] = ts[gd];
}

void solve(int rt, int gd){
    dfsg(rt, rt);
    dfsg2(rt, rt, sz[rt]);
    dfssub(cen, cen, 0, gd);
    //cerr << "solve " << cen << "  ";
    //printv(sub[cen], cerr);
    
    del[cen] = true;
    for(pii i : g[cen]){
        if(!del[i.F]) solve(i.F, gd + 1);
    }
}

ll oao = MAX;
void query(int u1, int u2, int v){
    
    for(int i = SZ - 1; i >= 0; i--){
        if(pr[i][v] == -1 || pr[i][esc] == -1) continue;
        if(pr[i][v] != pr[i][esc]) continue;
        int cen = pr[i][v];

        if(pr[i][u1] != cen || pr[i][u2] != cen){
            cout << "escaped\n";
            return;
        }

        if(in[i][u1] > in[i][u2]) swap(u1, u2);

        if(in[i][u2] <= in[i][v] && out[i][v] <= out[i][u2]) break;
        if(in[i][u2] <= in[i][esc] && out[i][esc] <= out[i][u2]) break;

        cout << "escaped\n";
        return;
    }

    ll ans = MAX;
    for(int i = SZ - 1; i >= 0; i--){
        if(pr[i][v] == -1) continue;

        int cen = pr[i][v];
        if(pr[i][u1] != cen || pr[i][u2] != cen){
            ans = min(ans, dpt[i][v] + st[i].query(in[i][cen], out[i][cen]));
            //cerr << "query " << i << " " << v << " " << "\n";
            //for(int j = in[i][cen]; j <= out[i][cen]; j++) cerr << st[i].query(j, j) << " ";
            //cerr << "\n";
            continue;
        }
        
        if(in[i][u1] > in[i][u2]) swap(u1, u2);
        if(in[i][u2] <= in[i][v] && out[i][v] <= out[i][u2]) continue;
        ans = min(ans, dpt[i][v] + st[i].query(in[i][cen], in[i][u2] - 1));
        ans = min(ans, dpt[i][v] + st[i].query(out[i][u2] + 1, out[i][cen]));
        /*if(in[i][v] <= in[i][u2] && out[i][u2] <= out[i][v]){
            ans = min(ans, dpt[i][v] + st[i].query(in[i][cen], in[i][v] - 1));
            ans = min(ans, dpt[i][v] + st[i].query(out[i][v] + 1, out[i][cen]));
        }
        else if(in[i][u2] <= in[i][v]){
            ans = min(ans, dpt[i][v] + st[i].query(in[i][cen], in[i][u2] - 1));
            ans = min(ans, dpt[i][v] + st[i].query(out[i][u2] + 1, in[i][v] - 1));
            ans = min(ans, dpt[i][v] + st[i].query(out[i][v] + 1, out[i][cen]));
        }
        else{
            ans = min(ans, dpt[i][v] + st[i].query(in[i][cen], in[i][v] - 1));
            ans = min(ans, dpt[i][v] + st[i].query(out[i][v] + 1, in[i][u2] - 1));
            ans = min(ans, dpt[i][v] + st[i].query(out[i][u2] + 1, out[i][cen]));
        }*/
    }

    //if(ans != oao) cerr << ans << " " << oao << "\n";
    //assert(ans == oao);
    if(ans == MAX) cout << "oo\n";
    else cout << ans << "\n";
    //if(oao == MAX) cout << "oo\n";
    //else cout << oao << "\n";
}

void dfsbf(int now, int p, int u1, int u2, ll d){
    if(now == esc) oao = -1;
    if(shop[now]) oao = min(oao, d);
    for(pii i : g[now]){
        if(i.F == p) continue;
        if(mp(now, i.F) == mp(u1, u2) || mp(now, i.F) == mp(u2, u1)) continue;
        dfsbf(i.F, now, u1, u2, d + i.S);
    }
}

int N = 20;
mt19937 rnd(2124123);
uniform_int_distribution<int> ud(1, 1000000000);
uniform_int_distribution<int> ud2(1, N);

int main(){
    StarBurstStream

    int q, s;
    cin >> n >> s >> q >> esc;
    //n = N;
    //s = 1;
    //q = N;
    //esc = ud2(rnd);
    init();

    for(int i = 1; i < n; i++){
        int u, v, w;
        cin >> u >> v >> w;
        //u = i; v = i + 1;
        //w = ud(rnd);

        g[u].eb(mp(v, w));
        g[v].eb(mp(u, w));
        e[i] = mp(u, v);
        //cerr << u << " " << v << " " << w << "\n";
    }

    for(int i = 0; i < s; i++){
        int c;
        cin >> c;
        //c = ud2(rnd);
        shop[c] = true;
        //cerr << "shop " << c << "\n";
    }

    solve(1, 0);

    /*cerr << "pr\n";
    for(int i = 0; i < SZ; i++){
        printv(pr[i], cerr);
    }
    cerr << "in\n";
    for(int i = 0; i < SZ; i++){
        printv(in[i], cerr);
    }
    cerr << "out\n";
    for(int i = 0; i < SZ; i++){
        printv(out[i], cerr);
    }*/
    
    for(int i = 0; i < q; i++){
        int eid, v;
        cin >> eid >> v;
        //eid = ud2(rnd); if(eid == n) eid--;
        //v = ud2(rnd);
        int u1 = e[eid].F, u2 = e[eid].S;
        //cerr << eid << " " << v << "\n";

        //oao = MAX;
        //dfsbf(v, v, u1, u2, 0);

        query(u1, u2, v);
    }

    return 0;
}

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