c_cpp 非排序数组中的最小元素

Posted 2021-05-14

// https://www.geeksforgeeks.org/kth-smallestlargest-element-unsorted-array/
#include <iostream>
using namespace std;

void minHeap (int a[], int i, int n) {
    int l=2*i+1, r = 2*i+2, smallest = i;
    if (l<n) {
        if (a[l] < a[smallest])
            smallest = l;
        if (r<n && a[r] < a[smallest])
            smallest = r;
        if (smallest!= i) {
            swap(a[i], a[smallest]);
            minHeap(a, smallest, n);
        }
    }
}
void extractMin (int a[], int n, int k) {
    int s;
    for (int i=0; i<k;i++) {
        s= a[0];
        a[0]= a[n-1-i];
        minHeap(a, 0, n-i);
    }
    cout<< s<< "\n";
}

int main() {
    int t;
    cin>>t;
    while (t-->0) {
        int n,k;
        cin>>n;
        int a[n];
        for (int i=0;i<n;i++)
            cin>>a[i];
        cin>>k;
        for (int i=n/2-1; i>=0; i--)
            minHeap(a, i, n);
        extractMin (a, n, k);
    }
}