Submission #564177

#	Time	Username	Problem	Language	Result	Execution time	Memory
564177		tamthegod	Race (IOI11_race)	C++14	21 / 100	2853 ms	262144 KiB

race

#include<iostream>
#include<iomanip>
#include<algorithm>
#include<stack>
#include<queue>
#include<string>
#include<string.h>
#include<cmath>
#include<vector>
#include<map>
#include<unordered_map>
#include<set>
#include<unordered_set>
#include<cstdio>
#include<bitset>
#include<chrono>
#include<random>
#include<ext/rope>
/* ordered_set
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
*/
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e6 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n, k;
vector<pair<int, int>> adj[maxN];
int vis[maxN], parCent[maxN], dp[maxN];
int depth[maxN], lg[maxN];
int f[maxN][21];
ll d[maxN];
map<ll, vector<ll>> mp[maxN];
ll res = oo;
void Log()
{
    for(int i=2; i<maxN; i++) lg[i] = lg[i / 2] + 1;
}
void predfs(int u, int par)
{
    for(pair<int, int> a : adj[u])
    {
        int v = a.fi, w = a.se;
        if(v == par) continue;
        d[v] = d[u] + w;
        depth[v] = depth[u] + 1;
        f[v][0] = u;
        for(int i=1; i<=lg[n]; i++)
            f[v][i] = f[f[v][i - 1]][i - 1];
        predfs(v, u);
    }
}
int lca(int u, int v)
{
    if(depth[u] < depth[v]) swap(u, v);
    int k = depth[u] - depth[v];
    for(int i=lg[n]; i>=0; i--)
    {
        if(k & (1 << i))
        {
            u = f[u][i];
            k -= (1 << i);
        }
    }
    if(u == v) return u;
    for(int i=lg[n]; i>=0; i--)
    {
        if(f[u][i] != f[v][i])
        {
            u = f[u][i];
            v = f[v][i];
        }
    }
    return f[u][0];
}
ll dist(int u, int v)
{
    return d[u] + d[v] - 2 * d[lca(u, v)];
}
ll Dist(int u, int v)
{
    return depth[u] + depth[v] - 2 * depth[lca(u, v)];
}
int dfs(int u, int par)
{
    dp[u] = 1;
    for(pair<int, int> a : adj[u])
    {
        int v = a.fi;
        if(v == par || vis[v]) continue;
        dp[u] += dfs(v, u);
    }
    return dp[u];
}
int Find_Centroid(int u, int par, int sz)
{
    for(pair<int, int> a : adj[u])
    {
        int v = a.fi;
        if(v == par || vis[v]) continue;
        if(dp[v] > sz / 2) return Find_Centroid(v, u, sz);
    }
    return u;
}
int Decompose(int u)
{
    int root = Find_Centroid(u, 0, dfs(u, 0));
    vis[root] = 1;
    for(pair<int, int> a : adj[root])
    {
        int v = a.fi;
        if(vis[v]) continue;
        parCent[Decompose(v)] = root;
    }
    return root;
}
void update(int u)
{
    for(int v=u; v; v=parCent[v])
    {
        if(!mp[v][k - dist(u, v)].empty())
        {
            for(int x : mp[v][k - dist(u, v)])
            {
                if(dist(u, x) == k) res = min(res, Dist(u, x));
            }
        }
        if(mp[v][dist(u, v)].empty()) mp[v][dist(u, v)].pb(u);
        else
        {
            if(mp[v][dist(u, v)].size() < 2) mp[v][dist(u, v)].pb(u);
            else if(Dist(mp[v][dist(u, v)][0], v) > Dist(u, v))
            {
                int x = mp[v][dist(u, v)][0];
                mp[v][dist(u, v)].clear();
                mp[v][dist(u, v)].pb(u);
                mp[v][dist(u, v)].pb(x);
            }
            else if(Dist(mp[v][dist(u, v)][1], v) > Dist(u, v))
            {
                mp[v][dist(u, v)].pop_back();
                mp[v][dist(u, v)].pb(u);
            }
            sort(mp[v][dist(u, v)].begin(), mp[v][dist(u, v)].end());
        }
        if(dist(u, v) == k) res = min(res, Dist(u, v));
    }
}
int best_path(int N, int K, int H[][2], int L[2])
{
    n = N;
    k = K;
    for(int i=0; i<n; i++)
    {
        H[i][0]++;
        H[i][1]++;
        adj[H[i][0]].pb({H[i][1], L[i]});
        adj[H[i][1]].pb({H[i][0], L[i]});
    }
    Log();
    predfs(1, 0);
    Decompose(1);
    for(int i=1; i<=n; i++) update(i);
    return res < oo ? res : -1;
}
void ReadInput()
{
    cin >> n >> k;
    for(int i=1; i<n; i++)
    {
        int u, v, w;
        cin >> u >> v >> w;
        u++;
        v++;
        adj[u].pb({v, w});
        adj[v].pb({u, w});
    }
}
void Solve()
{
    Log();
    predfs(1, 0);
    Decompose(1);
    for(int i=1; i<=n; i++) update(i);
    cout << (res < oo ? res : -1);
}

/*int main()
{
    freopen("x.inp", "r", stdin);
    ReadInput();
    Solve();
}
*/

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