Cod sursa(job #3272595)

Utilizator cinavalptopscalaCont laptop in scoala cinavalptopscala Data 30 ianuarie 2025 10:37:04
Problema Stramosi Scor 0
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 1.98 kb
#include <fstream>
#include <vector>
using namespace std;
//ifstream fin ("stramosi.in");
ofstream fout ("stramosi.out");
FILE *in_file = fopen("stramosi.in", "r");

const int DIM = 250001;
const int BUF_SIZE = 1115 * (1 << 10);

vector<int> G[DIM];
int boss[DIM], lvl[DIM], heavy[DIM], idx[DIM], head[DIM], nodes[DIM];
char buf[BUF_SIZE];
int buf_ptr = BUF_SIZE, max_ptr = BUF_SIZE;
int n, cnt;

int DFS(int);
void HeavyLite(int);
int kth(int, int);
int getInt();

int main() {
    int m, x, k;
    n = getInt();
    m = getInt();
    for(int i=1; i<=n; ++i) {
        x = getInt();
        G[x].push_back(i);
    }
    DFS(0);
    /*for(int i=0; i<=n; ++i) {
        fout << boss[i] << ' ' << lvl[i] << ' ' << heavy[i] << '\n';
    }*/
    HeavyLite(0);
    while(m--) {
        x = getInt();
        k = getInt();
        fout << kth(x, k) << '\n';
    }
    return 0;
}

int DFS(int x) {
    int my_cnt = 1, his_cnt, maxcnt = 0;
    for(int y : G[x]) {
        boss[y] = x;
        lvl[y] = lvl[x] + 1;
        his_cnt = DFS(y);
        if(his_cnt > maxcnt){
            heavy[x] = y;
            maxcnt = his_cnt;
        }
        my_cnt += his_cnt;
    }
    return my_cnt;
}
void HeavyLite(int x) {
    nodes[idx[x] = cnt++] = x;
    if(heavy[x]) {
        head[heavy[x]] = x;
        HeavyLite(heavy[x]);
    }
    for(int y : G[x]) {
        if(y == heavy[x]) continue;
        head[y] = y;
        HeavyLite(y);
    }
}
int kth(int x, int k) {
    int lvl_need = lvl[x] - k;
    if(lvl_need <= 0) return 0;
    while(lvl[head[x]] > lvl_need)
        x = boss[head[x]];
    return nodes[idx[head[x]] + (lvl_need - lvl[head[x]])];
}
int getInt() {
    int num = 0;
    do {
        if(buf_ptr >= max_ptr && max_ptr == BUF_SIZE) {
            buf_ptr = 0;
            max_ptr = fread(buf, sizeof(buf[0]), BUF_SIZE, in_file);
        }
        char c = buf[buf_ptr++];
        if(c >= '0' && c <= '9') {
            num *= 10;
            num += c - '0';
        }
        else break;
    } while(1);
    return num;
}