Submission #297163

#	Time	Username	Problem	Language	Result	Execution time	Memory
297163		Kastanda	Race (IOI11_race)	C++11	100 / 100	1018 ms	41488 KiB

race

/*
    Take me to church
    I'll worship like a dog at the shrine of your lies
    I'll tell you my sins and you can sharpen your knife
    Offer me that deathless death
    Good God, let me give you my life
*/
#include<bits/stdc++.h>
#include "race.h"
#define x first
#define y second
using namespace std;
const int N = 200005, MXK = 2000006;
int n, k, Mn = N, M[N], SZ[N], qu[N], H[N], D[N], B[MXK];
vector < pair < int , int > > Adj[N];
vector < int > A;
void DFSSZ(int v, int p = -1)
{
    SZ[v] = 1;
    for (auto u : Adj[v])
        if (!M[u.x] && u.x != p)
            DFSSZ(u.x, v), SZ[v] += SZ[u.x];
}
inline int Centroid(int v)
{
    DFSSZ(v);
    int _n = SZ[v], w = 1, p = -1;
    while (w)
    {
        w = 0;
        for (auto u : Adj[v])
            if (!M[u.x] && u.x != p && SZ[u.x] * 2 > _n)
                {p = v; v = u.x; w = 1; break;}
    }
    return (v);
}
void DFS(int v, int p)
{
    A.push_back(v);
    if (D[v] <= k)
        Mn = min(Mn, H[v] + B[k - D[v]]);
    for (auto u : Adj[v])
        if (!M[u.x] && u.x != p)
            H[u.x] = H[v] + 1, D[u.x] = min(D[v] + u.y, MXK - 2), DFS(u.x, v);
}
void UNDFS(int v, int p)
{
    B[D[v]] = B[MXK - 1];
    for (auto u : Adj[v])
        if (!M[u.x] && u.x != p)
            UNDFS(u.x, v);
}
inline void Solve(int v)
{
    H[v] = D[v] = 0;
    for (auto u : Adj[v])
        if (!M[u.x])
        {
            H[u.x] = H[v] + 1;
            D[u.x] = D[v] + u.y;
            DFS(u.x, v);
            for (int w : A)
                B[D[w]] = min(B[D[w]], H[w]);
            A.clear();
        }
    for (auto u : Adj[v])
        if (!M[u.x])
            UNDFS(u.x, v);
}
inline void Decompose()
{
    int l = 0, r = 0;
    qu[r ++] = 0;
    while (r - l)
    {
        int v = Centroid(qu[l ++]);
        Solve(v); M[v] = 1;
        for (auto u : Adj[v])
            if (!M[u.x])
                qu[r ++] = u.x;
    }
}
int best_path(int _n, int _k, int _E[200000][2], int _L[200000])
{
    n = _n; k = _k;
    //cin >> n >> k;
    memset(B, 63, sizeof(B)); B[0] = 0;
    for (int i = 0; i < n - 1; i ++)
    {
        Adj[_E[i][0]].push_back({_E[i][1], _L[i]});
        Adj[_E[i][1]].push_back({_E[i][0], _L[i]});
        //int a, b, c;
        //cin >> a >> b >> c;
        //Adj[a].push_back({b, c});
        //Adj[b].push_back({a, c});
    }
    int l = 0, r = 0;
    Decompose();
    if (Mn == N)
        Mn = -1;
    //printf("%d\n", Mn);
    //return 0;
    return (Mn);
}

Compilation message (stderr)

race.cpp: In function 'int best_path(int, int, int (*)[2], int*)':
race.cpp:97:9: warning: unused variable 'l' [-Wunused-variable]
   97 |     int l = 0, r = 0;
      |         ^
race.cpp:97:16: warning: unused variable 'r' [-Wunused-variable]
   97 |     int l = 0, r = 0;
      |                ^

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