Submission #396738

#	Time	Username	Problem	Language	Result	Execution time	Memory
396738		JerryLiu06	Race (IOI11_race)	C++14	0 / 100	3 ms	4940 KiB

race

#include <bits/stdc++.h>
#include "race.h"
 
using namespace std;

using pi = pair<int, int>;
using vpi = vector<pi>;

#define pb push_back
 
#define f first
#define s second

const int INF = 1000000010;
 
int N, K, ans = INF; vpi adj[200010]; int sub[200010]; bool vis[200010]; unordered_map<int, int> cur;
 
void DFS1(int X, int P) { 
    sub[X] = 1; for (pi Y : adj[X]) if (Y.f != P && !vis[Y.f]) { DFS1(Y.f, X); sub[X] += sub[Y.f]; } 
}
int getCent(int X, int P, int S) { 
    for (pi Y : adj[X]) if (Y.f != P && !vis[Y.f] && sub[Y.f] > S / 2) return getCent(Y.f, X, S); return X;
}
void DFS2(int X, int P, bool upd, int dist, int depth) {
    if (dist > K) return ; 
    
    if (upd) { if (cur.count(dist)) cur[dist] = min(cur[dist], depth); else cur[dist] = depth; }
    else { if (cur.count(K - dist)) ans = min(ans, cur[K - dist] + depth); }
 
    for (pi Y : adj[X]) if (Y.f != P && !vis[Y.f]) DFS2(Y.f, X, upd, dist + Y.s, depth + 1);
}
void decomp(int X) {
    DFS1(X, 0); int C = getCent(X, 0, sub[X]); vis[C] = true; cur[0] = 0;
 
    for (pi Y : adj[X]) if (!vis[Y.f]) { DFS2(Y.f, C, false, Y.s, 1); DFS2(Y.f, C, true, Y.s, 1); }
 
    cur.clear(); for (pi Y : adj[X]) if (!vis[Y.f]) decomp(Y.f);
}
int best_path(int _N, int _K, int H[][2], int L[]) {
    N = _N; K = _K; for (int i = 1; i < N; i++) { 
        int A = H[i][0] + 1; int B = H[i][1] + 1; 
        
        adj[A].pb({B, L[i]}), adj[B].pb({A, L[i]});
    }
    decomp(1); return (ans == INF ? -1 : ans);
}

Compilation message (stderr)

race.cpp: In function 'int getCent(int, int, int)':
race.cpp:22:5: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   22 |     for (pi Y : adj[X]) if (Y.f != P && !vis[Y.f] && sub[Y.f] > S / 2) return getCent(Y.f, X, S); return X;
      |     ^~~
race.cpp:22:99: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   22 |     for (pi Y : adj[X]) if (Y.f != P && !vis[Y.f] && sub[Y.f] > S / 2) return getCent(Y.f, X, S); return X;
      |                                                                                                   ^~~~~~

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