Submission #904811

#	Time	Username	Problem	Language	Result	Execution time	Memory
904811		Amirreza_Fakhri	Race (IOI11_race)	C++17	0 / 100	3 ms	10584 KiB

race

// In the name of the God 
#include <bits/stdc++.h>
#define ll long long
// #define int long long
#define pb push_back
#define F first
#define S second
#define mp make_pair
#define pii pair <int, int>
#define smin(x, y) (x) = min((x), (y))
#define smax(x, y) (x) = max((x), (y))
#define all(x) (x).begin(), (x).end()
using namespace std;

const int inf = 1e9+7;
const int mod = 998244353;
const int maxn = 2e5+5, maxk = 1e6+5;

int n, k, ans = inf, sz[maxn], mn[maxk];
bool mark[maxn];
vector <pii> adj[maxn], vec1;
vector <int> vec2;

void dfs1(int v, int p) {
    sz[v] = 1;
    for (pii e : adj[v]) {
        int u = e.F;
        if (u != p and !mark[u]) {
            dfs1(u, v); sz[v] += sz[u];
        }
    }
}

int dfs2(int v, int s, int p) {
    for (pii e : adj[v]) {
        int u = e.F;
        if (u != p and !mark[u] and sz[u] > s/2) return dfs2(u, s, v);
    }
    return v;
}

void dfs3(int v, int c, int h, int p) {
    if (c > k) return;
    vec2.pb(c); vec1.pb(mp(c, h));
    smin(ans, mn[k-c]+h);
    for (pii e : adj[v]) {
        int u = e.F;
        if (u != p and !mark[u]) dfs3(u, c+e.S, h+1, v);
    }
}

void cd(int v) {
    dfs1(v, v);
    v = dfs2(v, sz[v], v);
    mn[0] = 0; vec2.pb(0);
    for (pii e : adj[v]) {
        int u = e.F;
        if (!mark[u]) {
            dfs3(u, e.S, 1, v);
            for (pii x : vec1) smin(mn[x.F], x.S);
            vec1.clear();
        }
    }
    for (int x : vec2) mn[x] = inf;
    vec2.clear();
    mark[v] = 1;
    for (pii e : adj[v]) {
        int u = e.F;
        if (!mark[u]) cd(u);
    }
}

int best_path(int N, int K, int H[][2], int L[]) {
    n = N, k = K;
    for (int i = 0; i < n-1; i++) {
        adj[H[i][0]].pb(mp(H[i][1], L[i]));
        adj[H[i][1]].pb(mp(H[i][0], L[i]));
    }
    cd(0);
    return ans == inf ? -1 : ans;
}

// int32_t main() {
//     ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//     cin >> n >> k;
//     for (int i = 0; i < n-1; i++) {
//         int v, u, w; cin >> v >> u >> w;
//         adj[v].pb(mp(u, w));
//         adj[u].pb(mp(v, w));
//     }
//     fill(mn, mn+maxk, inf);
//     cd(0);
//     cout << (ans == inf ? -1 : ans) << '\n';
//     return 0;
// }

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