Submission #216556

#	Time	Username	Problem	Language	Result	Execution time	Memory
216556		LittleFlowers__	Race (IOI11_race)	C++14	100 / 100	488 ms	33752 KiB

race

#include <bits/stdc++.h>
using namespace std;
#define in ({int x=0;int c=getchar(),n=0;for(;!isdigit(c);c=getchar()) n=(c=='-');for(;isdigit(c);c=getchar()) x=x*10+c-'0';n?-x:x;})
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rnd(int l,int r){return l+rng()%(r-l+1);}
#define fasty ios_base::sync_with_stdio(0),cin.tie(0);
#define forinc(a,b,c) for(int a=b,_c=c;a<=_c;++a)
#define fordec(a,b,c) for(int a=b,_c=c;a>=_c;--a)
#define forv(a,b) for(auto&a:b)
#define fi first
#define se second
#define pb push_back
#define ii pair<int,int>
#define mt make_tuple
#define all(a) a.begin(),a.end()
#define reset(f, x) memset(f, x, sizeof(f))
#define bit(x,i) ((x>>(i-1))&1)
#define on(x,i) (x|(1ll<<(i-1)))
#define off(x,i) (x&~(1<<(i-1)))
#define gg exit(0);

//#define unx 1

#ifndef unx
    #include "race.h"
#endif

const int N=200010;

int n,cnt,k,ret;
int sz[N],dd[N],f[N*5];
vector<ii> val;
vector<ii> ad[N];


void dfs1(int u,int p=-1){
    sz[u]=1; cnt++;
    forv(v,ad[u]) if(!dd[v.fi] && v.fi!=p)
        dfs1(v.fi,u), sz[u]+=sz[v.fi];
}
int ftr(int u,int p=-1){
    forv(v,ad[u]) if(!dd[v.fi] && v.fi!=p && sz[v.fi]>cnt/2) return ftr(v.fi,u);
    return u;
}

void dfs2(int u,int p,int c,int d){
    if(c>k) return;
    val.push_back({c,d});
    forv(v,ad[u]) if(!dd[v.fi] && v.fi!=p && v.se+c<=k)
        dfs2(v.fi,u,c+v.se,d+1);
}

void ctr(int u){
    cnt=0; dfs1(u); dd[u=ftr(u)]=1;

    f[0]=0;
    vector<int> reval;
    forv(v,ad[u]) if(!dd[v.fi]){
        dfs2(v.fi,u,v.se,1);
        forv(i,val) if(f[k-i.fi]>-1) ret=min(ret,i.se+f[k-i.fi]);
        forv(i,val) f[i.fi]=f[i.fi]<0 ? i.se : min(f[i.fi],i.se), reval.push_back(i.fi);
        val.clear();
    }
    forv(i,reval) f[i]=-1;

    forv(v,ad[u]) if(!dd[v.fi]) ctr(v.fi);
}

int best_path(int n,int _k,int h[][2],int l[]){ k=_k; ret=n;
    forinc(i,0,n-2){
        int u=h[i][0], v=h[i][1], w=l[i];
        ad[u].push_back({v,w});
        ad[v].push_back({u,w});
    }
    reset(f,-1);
    ctr(0);
    return ret<n ? ret : -1;
}

#ifdef unx

main(){
    #define task "RACE"
    freopen(task".inp","r",stdin);
    //freopen(task".out","w",stdout);

    int n, k; cin>>n>>k;

    int H[100][2];
    int L[100];


    forinc(i,2,n){
        cin>>H[i-2][0]>>H[i-2][1];
    }
    forinc(i,2,n){
        cin>>L[i-2];
    }

    cout<<best_path(n,k,H,L);

}
#endif

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