Submission #1112051

#	Time	Username	Problem	Language	Result	Execution time	Memory
1112051		FucKanh	Race (IOI11_race)	C++14	9 / 100	131 ms	47176 KiB

race

#include "race.h"
#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>

using namespace std;

const ll maxn = 2e5 + 2;

ll f[(ll)1e6 + 2];
ll sz[maxn],h[maxn],k;
vector<pii> a[maxn];
ll ans = LLONG_MAX;
map<ll,ll> mp[maxn];

void dfs(ll u, ll w, ll pa) {
    for (pii tmp : a[u]) {
        ll wv,v; tie(v,wv) = tmp;
        if (v==pa) continue;
        h[v] = h[u] + 1;
        dfs(v,w+wv,u);

        ll t = mp[v][w+wv];
        mp[v][w+wv] = (t == 0) ? h[v] : min(t,h[v]);

        if (mp[u].size() < mp[v].size()) swap(mp[u],mp[v]);

        for (pii val : mp[v]) {
            if (val.second==0) continue;
            if (val.first - w < k && mp[u][k-val.first+w] != 0) {
                ans = min(ans, mp[u][k-val.first+w] - h[u] + val.second - h[u]);
            }
        }

        mp[u].insert(mp[v].begin(),mp[v].end());
        if (mp[u][w + k] != 0) {
            ans = min(ans, mp[u][w+k]-h[u]);
        }
    }

}

int best_path(int _n, int _k, int _h[][2], int _L[])
{
    k = _k;
    for (ll i = 0; i < _n - 1; i++){
        ll x = _h[i][0], y= _h[i][1];
        ll w = _L[i];
        a[x].push_back({y,w});
        a[y].push_back({x,w});
    }
    h[0] = 1;
    dfs(0,0,-1);
    return (int) ans == LLONG_MAX ? -1 : ans;
}

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