Submission #930905

#	Time	Username	Problem	Language	Result	Execution time	Memory
930905		Art_ogo	Race (IOI11_race)	C++17	21 / 100	196 ms	21972 KiB

race

#include <bits/stdc++.h>
#include "race.h"

#define ll long long
#define ve vector
#define fi first
#define se second

using namespace std;

const int MAXN = 1e5+10;

typedef pair<ll, ll> pll;

ve<pll> g[MAXN];
int sz[MAXN];
bool del[MAXN];
ve<pll> comp;
ll k;

void updsz(int v, int p){
    sz[v] = 1;
    for(auto& to : g[v])
        if(to.fi != p && !del[to.fi]){
            updsz(to.fi, v);
            sz[v] += sz[to.fi];
        }
}

int centroid(int v, int p, int ssz){
    for(auto& to : g[v])
        if(to.fi != p && !del[to.fi] && 2*sz[to.fi] > ssz)
            return centroid(to.fi, v, ssz);
    return v;
}

struct vertex{
    int sum, len, id;
};

void add(int v, int p, int len, int sum){
    comp.push_back({sum, len});
    for(auto& to : g[v])
        if(to.fi != p && !del[to.fi])
            add(to.fi, v, len + 1, to.se + sum);
}

int decomp(int v){
    updsz(v, v);
    int ssz = sz[v];
    int res = 1e9;
    v = centroid(v, v, ssz);
    del[v] = 1;

    map<ll, int> mp;
    mp[0] = 0;
    for(auto to : g[v]){
        if(!del[to.fi]){
            comp.clear();
            add(to.fi, v, 1, to.se);
            for(auto i : comp)
                if(mp.find(k - i.fi) != mp.end())
                    res = min<int>(res, mp[k - i.fi] + i.se);
            for(auto i : comp)
                if(mp.find(i.fi) == mp.end() || mp[i.fi] > i.se)
                    mp[i.fi] = i.se;
        }
    }
    for(auto to : g[v])
        if(!del[to.fi])
            res = min(res, decomp(to.fi));
    return res;
}


int best_path(int N, int K, int H[][2], int L[])
{
    k = K;
    for(int i = 0; i < N - 1; i++){
        int u = H[i][0], v = H[i][1], w = L[i];
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    int res = decomp(0);
    if(res == 1e9)
        return -1;
    return res;
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57