Cod sursa(job #2282938)

Utilizator CristyXtremeSimion Cristian CristyXtreme Data 14 noiembrie 2018 19:17:02
Problema Statistici de ordine Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.66 kb
#include <stdio.h>
#include <stdlib.h>

using namespace std;

void interschimba(int &a, int &b) {
    int aux = a;
    a = b;
    b = aux;
}

void alegere_pivot(int *v, int left, int right) {
    int poz1, poz2, poz3;
    poz1 = rand() % (right - left + 1) + left;
    poz2 = rand() % (right - left + 1) + left;
    poz3 = rand() % (right - left + 1) + left;
    if (v[poz1] < v[poz2])
        interschimba(poz1, poz2);
    if (v[poz2] < v[poz3])
        interschimba(poz2, poz3);
    interschimba(v[poz2], v[right]);
}

int partitionare(int *v, int left, int right) {
    alegere_pivot(v, left, right);
    int pivot = v[right], ileft = left, iright = right - 1;
    do {
        while (v[ileft] < pivot)
            ileft++;
        while (v[iright] > pivot)
            iright--;
        if (ileft < iright) {
            interschimba(v[ileft], v[iright]);
            ileft++;
            iright--;
        }
        else
            return ileft;
    }
    while (true);
}

int sdo(int *v, int k, int left, int right) {
    if (right == left)
        return v[left];
    if (right - left > 0) {
        int poz = partitionare(v, left, right);
        interschimba(v[poz], v[right]);
        if (poz + 1 == k)
            return v[poz];
        if (k < poz + 1)
            return sdo(v, k, left, poz - 1);
        return sdo(v, k, poz + 1, right);
    }
}

int main() {
    freopen("sdo.in", "r", stdin);
    freopen("sdo.out", "w", stdout);
    int n, k;
    scanf("%d %d", &n, &k);
    int numere[n];
    for (int i = 0; i < n; i++)
        scanf("%d", &numere[i]);
    printf("%d ", sdo(numere, k, 0, n - 1));
    return 0;
}