제출 #790478

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
790478		kilikuma	경주 (Race) (IOI11_race)	C++14	100 / 100	247 ms	32832 KiB

race

#include "race.h"
#include <bits/stdc++.h>
#define pii pair<int,int>
#define fi first
#define se second
#define pb push_back
using namespace std;
#define MAXN 200010
#define MAXK 1000010
vector<pii> adj[MAXN];
int N, K, siz[MAXN], res, b[MAXK];
bool vis[MAXN];
 
int dfsSize(int node, int prev) {
    siz[node] = 1;
    for(auto x : adj[node]) {
        if(x.fi != prev && !vis[x.fi]) siz[node] += dfsSize(x.fi, node);
    }
    return siz[node];
}
int dfsCentroid(int node, int prev, int S) {
    for(auto x : adj[node]) {
        if(x.fi != prev && !vis[x.fi] && siz[x.fi] > S/2) return dfsCentroid(x.fi, node, S);
    }
    return node;
}
 
vector<int> v;
vector<pii> vt;
void dfsSolve(int node, int prev, int len, int dub) {
    vt.pb({dub, len});
    v.pb(len);
    res = min(res, b[K-len]+dub);
    for(auto x : adj[node]) {
        if(x.fi != prev && !vis[x.fi] && len+x.se <= K) dfsSolve(x.fi, node, len+x.se, dub+1);
    }
}
 
void centroidDecomp(int node) {
    int S = dfsSize(node, node);
    node = dfsCentroid(node, node, S);
    vis[node] = 1;
    for(auto x : adj[node]) {
        if(!vis[x.fi] && x.se <= K) dfsSolve(x.fi, node, x.se, 1);
        for(auto y : vt) {
            b[y.se] = min(b[y.se], y.fi);
        }
        res = min(res, b[K]);
        vt.clear();
    }
    for(auto x : v) b[x] = N;
    v.clear();
    for(auto x : adj[node]) if(!vis[x.fi]) centroidDecomp(x.fi);
}
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]+1].pb({H[i][1]+1, L[i]});
        adj[H[i][1]+1].pb({H[i][0]+1, L[i]});
    }
    res = N;
    for(int i = 0; i <= K; i++) b[i] = N;
    centroidDecomp(1);
    return (res == N ? -1:res);
}

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