在數組中找第k小元素

package algorithm.apps;import utils.com.Swapper;/** * 在數組中找第k小元素 *  * @author Toy *  */public class Select_K_01 {public int partition(int[] a, int left, int right) {int ck = a[left];int i = left + 1;int j = right;while (true) {while (a[i] < ck) {i++;}while (a[j] > ck) {j--;}if (i >= j) {break;}Swapper.swap(a, i, j);i++;j--;}a[left] = a[j];a[j] = ck;return j;}public int select_K_01(int[] a, int left, int right, int k) {if (left == right) {return a[left];}int p = partition(a, left, right);int ck = p - left + 1;// System.out.println(left+" "+a[left]+" "+p+" "+ck+" "+k);if (ck >= k) {return select_K_01(a, left, p, k);} else {return select_K_01(a, p + 1, right, k - ck);}}/** * @param args */public static void main(String[] args) {int[] a = new int[] { 1, 2, 3, 4, 5, 6 };Select_K_01 s = new Select_K_01();int k = 6;int m = s.select_K_01(a, 0, a.length - 1, k);System.out.println("method 01: " + m);}}