Submission #705404

#	Time	Username	Problem	Language	Result	Execution time	Memory
705404		bLIC	Race (IOI11_race)	C++17	100 / 100	862 ms	40640 KiB

race

/**
 *  Author: Anil Byar
**/

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>

// using namespace __gnu_pbds;
using namespace std;

// template<class T>
// using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;



#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)(x).size()
#define ft first
#define sd second
#define pb push_back

// Source: https://codeforces.com/blog/entry/68809
// { start
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '"' << x << '"';}
void __print(const string &x) {cerr << '"' << x << '"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
// } end


typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<pll> vll;
typedef vector<vi> vvi;
typedef vector<vii> vvii;
typedef vector<vl> vvl;

#define dbg if(0)

const ll MOD = 1e9+7;
const ll MOD9 = 998244353;
const ll INFLL = 1e18+5;
const int INF = 1e9;
const int maxN = 2e5+5;
const int maxK = 1e6+5;

void printbit(int x, int len) {string s="\n";while(len--){s=((x%2)?'1':'0')+s;x/=2;} cout<<s;}

template<class T>
istream& operator>>(istream&in, vector<T>&v){
    for (T& x:v) in>>x;
    return in;
}
template<class T>
ostream& operator<<(ostream&out, vector<T>&v){
    for (T& x:v) out<<x<<' ';
    cout<<'\n';
    return out;
}

int mnhighways[maxK];
int ans, k;

struct Edge{
    int v, w;
    bool operator==(Edge e){
        return v==e.v;
    }
};
struct Centroid{
    std::vector<std::vector<Edge>> adj;
    std::vector<int> parent, stree;
    const long long INF = 1e9;
    

    Centroid(std::vector<std::vector<Edge>>& _adj):adj(_adj){
        parent.resize((int)_adj.size());
        stree.resize((int)_adj.size());
    }

    void build(int node = 1, int par = -1){
        int n = dfssize(node, par);
        int centroid = dfscentroid(node, par, n);
        parent[centroid] = par;

        auto tmp = adj[centroid];
        adj[centroid].clear();

        for (Edge y:tmp){
            work(y.v, centroid, y.w, 1);
            upd(y.v, centroid, y.w, 1);
        }

        for (Edge y:tmp){
            del(y.v, centroid, y.w, 1);
        }

        for (Edge y:tmp) {
            int x = y.v, w = y.w;
            Edge tmp = {centroid, -1};
            adj[x].erase(find(all(adj[x]), tmp));
            build(x, centroid);
        }
    }

    int dfssize(int node, int par){
        stree[node] = 1;
        for (Edge y:adj[node]){
            int x = y.v;
            if (x==par) continue;
            dfssize(x, node);
            stree[node] += stree[x];
        }
        return stree[node];
    }

    int dfscentroid(int node, int par, int n){
        for (Edge y:adj[node]){
            int x = y.v;
            if (x==par) continue;
            if (stree[x]>n/2) return dfscentroid(x, node, n);
        }
        return node;
    }

    void work(int node, int par, int h, int dep){
        if (h>k) return;
        ans = min(ans, dep + mnhighways[k-h]);
        for (Edge x:adj[node]){
            if (x.v==par) continue;
            work(x.v, node, h+x.w, dep+1);
        }
    }

    void upd(int node, int par, int h, int dep){
        if (h>k) return;
        mnhighways[h] = min(mnhighways[h], dep);
        for (Edge x:adj[node]){
            if (x.v==par) continue;
            upd(x.v, node, h+x.w, dep+1);
        }
    }

    void del(int node, int par, int h, int dep){
        if (h>k) return;
        for (Edge x:adj[node]){
            if (x.v==par) continue;
            del(x.v, node, h+x.w, dep+1);
        }
        mnhighways[h] = INF;
    }
};

int best_path(int N,int K, int H[][2],int L[]){
    vector<vector<Edge>> tadj(N);
    for (int i = 0;i<N-1;i++){
        int u = H[i][0], v = H[i][1], w = L[i];
        tadj[u].pb({v, w});
        tadj[v].pb({u, w});
    }
    k = K;
    ans = INF;
    memset(mnhighways, 127, sizeof(mnhighways));
    mnhighways[0] = 0;
    Centroid ctr(tadj);
    ctr.build(0, -1);
    if (ans==INF) return -1;
    return ans;
}

Compilation message (stderr)

race.cpp: In member function 'void Centroid::build(int, int)':
race.cpp:127:26: warning: unused variable 'w' [-Wunused-variable]
  127 |             int x = y.v, w = y.w;
      |                          ^

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 57 / 57