Cod sursa(job #2778788)

Utilizator tryharderulbrebenel mihnea stefan tryharderul Data 2 octombrie 2021 10:50:45
Problema Stramosi Scor 90
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 1.55 kb
#include <bits/stdc++.h>
#define NMAX 250003
#define log 19

using namespace std;

int n, m;
int d[NMAX][log];

int k_ancestor(int x, int y) {
    for(int i = log-1;i >= 0; i--)
        if((1<<i) & y)
            x = d[x][i];
    return x;

}

class InParser {
private:
	FILE *fin;
	char *buff;
	int sp;

	char read_ch() {
		++sp;
		if (sp == 4096) {
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}

public:
	InParser(const char* nume) {
		fin = fopen(nume, "r");
		buff = new char[4096]();
		sp = 4095;
	}

	InParser& operator >> (int &n) {
		char c;
		while (!isdigit(c = read_ch()) && c != '-');
		int sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}

	InParser& operator >> (long long &n) {
		char c;
		n = 0;
		while (!isdigit(c = read_ch()) && c != '-');
		long long sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}
};

int main()
{
    InParser in("stramosi.in");
    freopen("stramosi.out","w",stdout);
    in >> n >> m;
    for(int i = 1; i <= n; i++) {
        int t;
        in >> t;
        d[i][0] = t;
        for(int j = 1; j < log; j++)
            d[i][j] = d[d[i][j-1]][j-1];
    }
    while(m--) {
        int x, y;
        in >> x >> y;
        printf("%d\n",k_ancestor(x,y));
    }
    return 0;
}