Submission #1004904

#	Time	Username	Problem	Language	Result	Execution time	Memory
1004904		YassirSalama	Race (IOI11_race)	C++17	9 / 100	69 ms	39764 KiB

race

// #include "race.h"
#include <bits/stdc++.h>
using namespace std;
const int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1};
#define endl "\n"
using ull=unsigned long long;
using ll=long long;
using pii=pair<int,int>;
const int mod=1e9+7;
#define OVL(x,s) for(auto y:x) cout<<y<<s; cout<<"\n";
template <typename T> istream& operator>>(istream& is, vector<T> &a) {
    copy_n(istream_iterator<T>(is), a.size(), a.begin()); return is;}
#ifdef IOI
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
 
void dbg_out() { cout << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cout << ' ' << H; dbg_out(T...); }
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__);
#else
#define dbg(...) 1337;
#endif
#define pb push_back
#define F first
#define S second
#define all(v) v.begin(),v.end()
const int mxN=2e5+100;
int k;
int n;
vector<pii> v[mxN];
ll ans=1e9;
ll sz[mxN];
ll d1[mxN];//using weight of the edge
ll d2[mxN];//jut dist (weight=1)
void dfs(int node,int par,ll d=0){
    d2[node]=d2[par]+1;
    d1[node]=d;
    sz[node]=1;
    for(auto x:v[node]){
        if(x.F==par) continue;
        dfs(x.F,node,d+x.S);
        sz[node]+=sz[x.F];
    }
}
map<ll,ll> mp[mxN];
void dfs2(int node,int par){
    int bc=-1;
    ll bs=0;
    for(auto x:v[node]){
        if(x.F!=par&&sz[x.F]>bs)
            bs=sz[x.F],bc=x.F;
        if(x.F!=par){
            dfs2(x.F,node);
        }
    }
    if(bc!=-1){
        swap(mp[node],mp[bc]);
    }
    mp[node][d1[node]]=d2[node];
    if(mp[node].count(d1[node]+k)>0){
    //     // dbg(node,-d2[node],mp[node][d1[node]+k])
        ans=min(ans,-d2[node]+mp[node][d1[node]+k]);
    }
    for(auto x:v[node]){
        if(x.F==par||x.F==bc) continue;
        for(auto it:mp[x.F]){
            ll z=k-it.F+2*d1[node];
            if(mp[node].count(z)>0){
                // dbg(node,x.F,t)
                ans=min(ans,mp[node][z]+it.S);
            }
        }
        for(auto it:mp[x.F]){
            if(mp[node].count(it.F)>0)
                mp[node][it.first]=min(mp[node][it.first],
                    it.second);
            else mp[node][it.F]=it.S;
        }
    }
}


int best_path(int N, int K, int H[][2], int L[]){
    n=N;
    k=K;
    for(int i=0;i+1<n;i++){
        v[H[i][0]].pb({H[i][1],L[i]});
        v[H[i][1]].pb({H[i][0],L[i]});
    }
    dfs(0,0);
    dfs2(0,0);

    if(ans==1e9) return -1;
    return ans;

}











#ifdef IOI
// #include "race.h"
#include <stdio.h>
#include <stdlib.h>

#define MAX_N 500000

static int N, K;
static int H[MAX_N][2];
static int L[MAX_N];
static int solution;

inline 
void my_assert(int e) {if (!e) abort();}

void read_input()
{
    int i;
    my_assert(2==scanf("%d %d",&N,&K));
    for(i=0; i<N-1; i++)
        my_assert(3==scanf("%d %d %d",&H[i][0],&H[i][1],&L[i]));
    my_assert(1==scanf("%d",&solution));
}

int main()
{
    int ans;
    read_input();
    ans = best_path(N,K,H,L);
    if(ans==solution)
        printf("Correct.\n");
    else
        printf("Incorrect. Returned %d, Expected %d.\n",ans,solution);

    return 0;
}
#endif

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