제출 #994458

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
994458		pannenkoek	경주 (Race) (IOI11_race)	C++17	100 / 100	356 ms	110780 KiB

race

#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define pb push_back
#define fi first
#define se second

using ll = long long;
using ld = long double;
using pii = pair<ll, ll>;

const int MAXN = 2e5 + 5;
vector<pii> adj[MAXN];
map<ll, ll> poss[MAXN]; 
ll off[MAXN], cost_off[MAXN];
ll res = 1e18;
int k;

void dfs(ll v, ll p){
    poss[v][0] = 0;
    for(auto [u, d]: adj[v]){
        if(u == p) continue;
        dfs(u, v);
        off[u] += d;
        cost_off[u]++;
        if(poss[u].size() > poss[v].size()) {
            swap(off[u], off[v]);
            swap(cost_off[u], cost_off[v]);
            swap(poss[u], poss[v]);
        }
        set<ll> new_entries;
        map<ll, ll> old_vals;
        for(auto [dis, cost]: poss[u]){
            ll real_dis = dis + off[u];
            if(real_dis > k) continue;
            ll miss = k - real_dis - off[v];
            if(poss[v].count(miss) && !new_entries.count(miss)){
                ll old_cost = poss[v][miss];
                if(old_vals.count(miss)) {
                    old_cost = old_vals[miss]; 
                }
                res = min(old_cost + cost_off[u] + cost_off[v] + cost, res);
            }
            real_dis -= off[v];
            if(poss[v].count(real_dis)) {
                old_vals[real_dis] = poss[v][real_dis];
                poss[v][real_dis] = min(poss[v][real_dis], cost + cost_off[u] - cost_off[v]);
            } else {
                poss[v][real_dis] = cost + cost_off[u] - cost_off[v];
                new_entries.insert(real_dis);
            }
        }
        poss[u] = {};
    }
}

int best_path(int N, int K, int H[][2], int L[]) {
    rep(i, 0, N) {
        adj[i] = {};
        poss[i] = {};
        off[i] = 0;
    }
    k = K;
    rep(i, 0, N - 1) {
        adj[H[i][0]].pb({H[i][1], L[i]});
        adj[H[i][1]].pb({H[i][0], L[i]});
    }
    dfs(0, -1); 
    if(res < 1e18) return res;
    else return -1;
}

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