Submission #1211525

#	Time	Username	Problem	Language	Result	Execution time	Memory
1211525		Br3ad	Race (IOI11_race)	C++20	0 / 100	3 ms	6720 KiB

race

#include <iostream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <numeric>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>

using namespace std;
#define ll long long
#define ull unsigned long long
#define f first
#define s second
#define PF push_front
#define PB push_back
#define MP make_pair
#define pi pair<int, int>

#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()

#define max(a, b) ((a > b)? a : b)
#define min(a, b) ((a < b)? a : b)
#define max3(a, b, c) max(max(a, b), c)
#define min3(a, b, c) min(min(a, b), c)

const int N = 2e5 + 5;
const int M = 1e9 + 7; 
const int inf = 0x3f3f3f3f;
const ll int INF = 1e18;

int _n, _k;
map<int, int> mp;
vector<pi> adj[N];
vector<int> sz(N), val(N);
vector<bool> processed(N, false);

int get_subtree_size(int cur, int prev = -1){
    sz[cur] = 1;
    for(auto [child, _] : adj[cur]){
        if(processed[child] || child == prev) continue;
        sz[cur] += get_subtree_size(child, cur);
    }
    return sz[cur];
}

int get_centroid(int thres, int cur, int prev = -1){
    for(auto [child, _] : adj[cur]){
        if(processed[child] || child == prev) continue;
        if(sz[child] >= thres) return get_centroid(thres, child, cur);
    }
    return cur;
}

int ans = N;
void get_cnt(int cur, int prev, bool filling, int depth, int cnt = 1){
    if(depth > _k) return;

    if(filling){
        if(mp[depth] == 0) mp[depth] = cnt;
        else mp[depth] = min(mp[depth], cnt);
    }else {
        int tmp = mp[_k - depth];
        if(mp[tmp]) ans = min(ans, cnt + mp[tmp]);
    }

    for(auto [child, w] : adj[cur]){
        if(processed[child] || child == prev) continue;
        get_cnt(child, cur, filling, depth+w, cnt+1);
    }
}

void centroid_decomp(int node = 1){
    int centroid = get_centroid(get_subtree_size(node) >> 1, node);
    processed[centroid] = true;

    mp.clear();
    for(auto [child, w] : adj[centroid]){
        if(processed[child]) continue;
        get_cnt(child, centroid, false, w);
        get_cnt(child, centroid, true, w);
    }

    for(auto [child, _] : adj[centroid]){
        if(!processed[child]) centroid_decomp(child);
    }
}

int best_path(int n, int k, int H[][2], int L[]){

    _n = n;
    _k = k;

    for(int i = 0; i < n-1; i++){
        int a = H[i][0], b = H[i][1];
        adj[a].PB({b, L[i]});
        adj[b].PB({a, L[i]});
    }
 
    centroid_decomp();

    if(ans == N) ans = -1;
    return ans;
}

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