Cod sursa(job #1625698)

Utilizator Tzappy90Mihalache Constantin Tzappy90 Data 2 martie 2016 20:13:42
Problema Statistici de ordine Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 1.14 kb
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <fstream>
#include <iostream>
#include <vector>

typedef unsigned int uint;

void swap(uint *a, uint *b)
{
    if (*a == *b) {
        return;
    }
    *a = *a ^ *b;
    *b = *a ^ *b;
    *a = *a ^ *b;
}

int partition(std::vector<uint> &v, uint lower, uint upper)
{
    uint pivot = v[upper];
    uint i = lower;
    for (uint j = lower; j < upper; j++) {
        if (v[j] <= pivot) {
            swap(&v[j], &v[i++]);
        }
    }
    swap(&v[i], &v[upper]);
    return i;
}

uint find_kth_min(std::vector<uint> &v, uint lower, uint upper, uint k)
{
    uint p;
    do {
        p = partition(v, lower, upper);
        if (p == k)
            break;
        if (p < k) {
            lower = p + 1;
        } else {
            upper = p - 1;
        }
    } while (lower < upper);

    return v[k];
}

int main(void)
{
    std::ifstream f("sdo.in");
    std::ofstream g("sdo.out");
    uint n, k;
    f >> n >> k;
    std::vector<uint> v(n);
    for (uint i = 0; i < n; i++) {
        f >> v[i];
    }
    g << find_kth_min(v, 0, v.size() - 1, k - 1) << '\n';
    f.close();
    g.close();
}