int *klargest(int list[], int n, int k) {
int i, last;
if (n == k)
return list+n;
last = 0;
for (i = 1; i < n; i++)
if (list[i] > list[0])
swap(&list[++last], &list[i]);
swap(&list[last], &list[0]);
if (k <= last + 1)
return klargest(list, last+1, k);
else
return klargest(list+last+1, n-last-1, k-last-1);
}
void test_klargest() {
int list[][5] = {
{1, 2, 3, 4, 5},
{2, 4, 3, 5, 1},
{1, 2, 5, 4, 3},
{5, 4, 3, 2, 1},
{1, 1, 2, 2, 2},
{1, 1, 1, 1, 1}
};
int list0[] = {1};
int i, *p, *k;
printf("test_klargest\n");
for (i = 0; i < 6; i++) {
k = klargest(list[i], 5, 4);
for (p = list[i]; p != k; p++)
printf("%d ", *p);
printf("\n");
}
k = klargest(list0, 1, 1);
for (p = list0; p != k; p++)
printf("%d ", *p);
printf("\n");
}
int main ()
{
int arr[] = {2, 5, 7, 1, 8, 10, 14, 17, 20, 25, 40, 2, 3, 5, 200};
klargest (arr, sizeof(arr)/sizeof(arr[0]), 15);
return 0;
}
