Submission #866043

#	Time	Username	Problem	Language	Result	Execution time	Memory
866043		dpsaveslives	Race (IOI11_race)	C++17	0 / 100	5 ms	21336 KiB

race

#include "race.h"
#include <bits/stdc++.h>
#define ll long long
#define f first
#define s second
using namespace std;
const int MAXN = 2e5+10;
vector<pair<ll,ll>> adj[MAXN];
map<ll,ll> help[MAXN];
ll dep[MAXN], dist[MAXN],ans;
int k,n;
void dfs(int u, int p, int de, ll di){
    dep[u] = de; dist[u] = di;
    help[u][di] = de;
    for(auto pa : adj[u]){
        if(pa.f != p){
            dfs(pa.f,u,dep[u]+1,dist[u]+pa.s);
        }
    }
}
void comb(int u, int p){
    int tar = k+2*dist[u];
    for(auto pa : adj[u]){
        int v = pa.f;
        if(v != p){
            comb(v,u);
            if(help[v].size() > help[u].size()) swap(help[v],help[u]);
            for(auto x : help[v]){
                if(help[u].find(tar-x.f) != help[u].end()){
                    ans = min(ans,help[u][tar-x.f]+x.s-2*dep[u]);
                }
            }
            for(auto x : help[v]){
                if(help[u].find(x.f) != help[u].end()){
                    help[u][x.f] = min(help[u][x.f],x.s);
                }
                else{
                    help[u].insert(x);
                }
            }
        }
    }
}
int best_path(int N, int K, int H[][2], int L[]){
    for(int i = 0;i<N;++i){
        int u = H[i][0], v = H[i][1], w = L[i];
        adj[u].push_back({v,w}); adj[v].push_back({u,w});
    }
    dfs(0,-1,0,0);
    n = N; k = K; ans = INT_MAX;
    comb(0,-1);
    if(ans != INT_MAX) return ans;
    else return -1;
}

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