Cod sursa(job #1402076)

Utilizator IonSebastianIon Sebastian IonSebastian Data 26 martie 2015 12:07:01
Problema Statistici de ordine Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 0.85 kb
#include <cstdio>

using namespace std;

FILE *in, *out;

const int MAX_N = 3000000;

int v[MAX_N];

int n, k;

void schimb(int &a, int &b)
{
    int x = a;
    a = b;
    b = x;
}

void part3(int st, int dr, int &p, int &u)
{
    p = st;
    u = dr-1;
    int i = st;
    while(i <= u)
    {
        if(v[i] < v[dr])
            schimb(v[p++], v[i++]);
        else if(v[i] == v[dr]) i++;
        else schimb(v[u--], v[i]);
    }
    u++;
    schimb(v[u],v[dr]);
}

int sdo(int st, int dr, int k)
{
    int p, u;
    part3(st, dr, p, u);
    if(p <= k && u >= k) return v[p];
    if(p > k) return sdo(st, p-1, k);
    return sdo(u+1,dr,k);
}

int main()
{
    in = fopen("sdo.in", "r");
    out = fopen("sdo.out", "w");

    fscanf(in, "%d%d", &n, &k);

    for(int i = 1; i <= n; i++)
        fscanf(in, "%d", &v[i]);

    fprintf(out, "%d", sdo(1,n,k));
    return 0;
}