Submission #291120

#	Time	Username	Problem	Language	Result	Execution time	Memory
291120		alexandra_udristoiu	Valley (BOI19_valley)	C++14	23 / 100	811 ms	48936 KiB

valley

#include<iostream>
#include<vector>
#define DIM 100005
#define INF 1000000000000000LL
#define f first
#define s second
using namespace std;
int n, k, i, q, x, y, ii, c, rad, nod;
int niv[DIM], a[18][DIM], sh[DIM], b[DIM];
long long d[DIM], d2[18][DIM], sum[18][DIM], sol, tot;
pair<int, int> w[DIM];
vector< pair<int, int> > v[DIM];
void dfs(int nod, int t){
    d[nod] = INF;
    if(sh[nod] == 1){
        d[nod] = 0;
    }
    for(int i = 0; i < v[nod].size(); i++){
        int vecin = v[nod][i].f;
        if(vecin != t){
            a[0][vecin] = nod;
            sum[0][vecin] = v[nod][i].s;
            niv[vecin] = 1 + niv[nod];
            dfs(vecin, nod);
            d[nod] = min(d[nod], d[vecin] + v[nod][i].s);
        }
    }
}
int main(){
    cin>> n >> k >> q >> rad;
    for(i = 1; i < n; i++){
        cin>> x >> y >> c;
        w[i] = make_pair(x, y);
        v[x].push_back( make_pair(y, c) );
        v[y].push_back( make_pair(x, c) );
    }
    for(i = 1; i <= k; i++){
        cin>> x;
        sh[x] = 1;
    }
    dfs(rad, 0);
    for(i = 1; i <= n; i++){
        d2[0][i] = sum[0][i] + d[ a[0][i] ];
    }
    for(ii = 1; (1 << ii) < n; ii++){
        for(i = 1; i <= n; i++){
            a[ii][i] = a[ii - 1][ a[ii - 1][i] ];
            if(a[ii][i] != 0){
                sum[ii][i] = sum[ii - 1][i] + sum[ii - 1][ a[ii - 1][i] ];
                d2[ii][i] = min(d2[ii - 1][i], sum[ii - 1][i] + d2[ii - 1][ a[ii - 1][i] ]);
            }
        }
    }
    for(i = 2; i <= n; i++){
        b[i] = 1 + b[i / 2];
    }
    for(; q; q--){
        cin>> ii >> x;
        if(niv[ w[ii].f ] > niv[ w[ii].s ]){
            y = w[ii].f;
        }
        else{
            y = w[ii].s;
        }
        ii = niv[x] - niv[y];
        nod = x;
        while(ii > 0){
            nod = a[ b[ii] ][nod];
            ii -= (1 << b[ii]);
        }
        if(nod != y){
            cout<<"escaped\n";
            continue;
        }
        sol = d[x];
        nod = x;
        tot = 0;
        ii = niv[x] - niv[y];
        while(ii != 0){
            sol = min(sol, tot + d2[ b[ii] ][nod]);
            tot += sum[ b[ii] ][nod];
            ii -= (1 << b[ii]);
        }
        if(sol >= INF){
            cout<<"oo\n";
        }
        else{
            cout<< sol <<"\n";
        }
    }
}

Compilation message (stderr)

valley.cpp: In function 'void dfs(int, int)':
valley.cpp:18:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     for(int i = 0; i < v[nod].size(); i++){
      |                    ~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 27
• Subtask 3: 23 / 23
• Subtask 4: 0 / 41