Submission #410052

#	Time	Username	Problem	Language	Result	Execution time	Memory
410052		definitelynotmee	Towns (IOI15_towns)	C++98	0 / 100	17 ms	348 KiB

towns

#include <bits/stdc++.h>
//#include "towns.h"
#define mp make_pair
#define mt make_tuple
#define ff first
#define ss second
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const ll INFL = (1LL<<62)-1;
const int INF = (1<<30)-1;
const int MAXN = 0;

int getDistance(int i, int j);

int hubDistance(int n, int sub){

    vector<int> ds (n,0), db(n,0), da(n,-1);

    int a = 0, b;
    int maxi = -1;
    for(int i = 1; i < n; i++){
        ds[i] = getDistance(0,i);
        if(ds[i] > maxi)
            maxi = ds[i], b = i;
    }
    maxi = ds[b];
    db[0] = ds[b];
    for(int i = 1; i < n; i++){
        if(i==b)
            continue;
        db[i] = getDistance(b,i);
        if(db[i] > maxi)
            maxi = db[i], a = i;
    }
    da[a] = 0;
    da[b] = db[a];
    da[0] = ds[a];
    vector<int> dlca(n,0), v(n,0);
    for(int i = 0; i < n; i++){
        dlca[i] = (db[0] + db[i] - ds[i])>>1;
    }
    iota(v.begin(), v.end(), 0);
    sort(v.begin(),v.end(),[&](int x, int y){
        return dlca[x] > dlca[y];
    });
    vector<bool> type(n,0);
    // se type = 1, faz parte da subarvore de s

    int resp = max(ds[a] + db[a] - ds[b],ds[b] + da[b] - ds[a])>>1; 
    // resposta comeca com o ponto do caminho (a,b) que intersecta com o caminho de (s,a) e (s,b)
    type[0] = 1;
    vector<int> retirar;
    for(int i = 1; i < n; i++){
        int cur = v[i];
        if(dlca[cur] == dlca[v[i-1]]){
            type[cur] = 1;
            retirar.push_back(cur);
            continue;
        }
        if(da[cur] == -1)
            da[cur] = getDistance(a,cur);
        int d1 = (da[cur] + db[a] - db[cur])>>1;
        int d2 = (db[cur] + da[b] - da[cur])>>1;
        if(max(d1,d2) > resp){
            break;
        }
        resp = max(d1,d2);
        type[cur] = 1;
        retirar.clear();
        retirar.push_back(cur);
    }
    for(int i : retirar)
        type[i] = 0;
    

    return resp;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:17:28: warning: unused parameter 'sub' [-Wunused-parameter]
   17 | int hubDistance(int n, int sub){
      |                        ~~~~^~~
towns.cpp:28:16: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   28 |     maxi = ds[b];
      |                ^

• Subtask 1: 0 / 13
• Subtask 2: 0 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 39