Submission #1086242

#	Time	Username	Problem	Language	Result	Execution time	Memory
1086242		rayan_bd	Race (IOI11_race)	C++17	43 / 100	3063 ms	40272 KiB

race

#include <bits/stdc++.h>

using namespace std;


#define getar(ar,n) for(int i=0;i<n;++i) cin>>ar[i]
#define show(n) cout<<n<<'\n'
#define aint(v) v.begin(), v.end()
#define br cout<<"\n"
#define pb push_back
#define nl '\n'
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define ret return
#define ll long long
#define ld long double
#define sza(x) ((int)x.size())

const int mxNN = 2e5+1000;
const int mxN = 1e6 + 500;
const int MOD = 1e9 + 7;
const int INF = 1e9;
const ld EPS = 1e-9;

vector<pair<int,int>> adj[mxNN];
vector<int> dp(mxN,INF);
vector<bool> ok(mxNN,0);
int sz[mxNN],K,ans=INF;

void dfs(int node,int par){
    sz[node]=1;
    for(auto it:adj[node]){
        if(it.first==par||ok[node]) continue;
        dfs(it.first,node);
        sz[node]+=sz[it.first];
    }
}

int find(int node,int par,int n){
    for(auto it:adj[node]){
        if(it.first==par||ok[node]) continue;
        if(sz[it.first]*2>n){
            return find(it.first,node,n);
        }
    }
    return node;
}



void path_finder(int u,int par,int h,int tot){
    if(tot>K) return;
    ans=min(ans,dp[K-tot]+h);
    for(auto it:adj[u]){
        if(it.first!=par&&!ok[it.first]){
            path_finder(it.first,u,h+1,tot+it.second);
        }
    }
}

void path_optimize(int u,int par,int h,int tot){
    if(tot>K) return;
    dp[tot]=min(dp[tot],h);
    for(auto it:adj[u]){
        if(it.first!=par&&!ok[it.first]){
            path_optimize(it.first,u,h+1,tot+it.second);
        }
    }
}

void dp_reset(int u,int par,int tot){
    if(tot>K) return;
    dp[tot]=INF;
    for(auto it:adj[u]){
        if(it.first!=par&&!ok[it.first]){
            dp_reset(it.first,u,tot+it.second);
        }
    }
}

void decompose(int u){
    dfs(u,-1);
    int cen=find(u,-1,sz[u]);
    dp[0]=0;
    for(auto it:adj[cen]){
        if(!ok[it.first]){
            path_finder(it.first,cen,1,it.second);
            path_optimize(it.first,cen,1,it.second);
        }
    }
    dp_reset(cen,-1,0);
    ok[cen]=1;
    for(auto it:adj[cen]){
        if(!ok[it.first]){
            decompose(it.first);
        }
    }
}

int best_path(int n,int k,int h[][2],int l[]){
    for(int i=0;i<n-1;++i){
        adj[h[i][0]].pb({h[i][1],l[i]});
        adj[h[i][1]].pb({h[i][0],l[i]});
    }
    K=k;
    decompose(0);
    return ans>=INF?-1:ans;
}

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