第4天 调整数组顺序使奇数和位于偶数前面

题目：调整数组顺序使奇数和位于偶数前面

输入：校验输入异常（为空，长度为0）

测试：

/** *  面试题14 调整数组顺序使奇数和位于偶数前面 *   *  2014-1-18 */public class ReorderArray {public int[] reorderArray(int[] arr) {if (arr == null || arr.length <= 0) {throw new NullPointerException();}int left = 0;int right = arr.length - 1;while (left < right) {// 向后和向前遍历都需要判断是否越界while (left < arr.length && !moveToLeft(arr[left])) {left++;}while (right >= 0 && moveToLeft(arr[right])) {right--;}if (left < right) {swap(arr, left, right);left++;right--;}}return arr;}public boolean equal(int[] arr1, int[] arr2) {for (int i = 0; i < arr1.length; i++) {if (arr1[i] != arr2[i]) {return false;}}return true;}/** * 提高扩展性，如果需要修改排序条件，只需修改此函数 *  * @param value * @return */private boolean moveToLeft(int value) {return (value & 0x1) == 0;}private void swap(int[] arr, int indexOne, int indexTwo) {int temp = arr[indexOne];arr[indexOne] = arr[indexTwo];arr[indexTwo] = temp;}public static void main(String[] args) {boolean flag = true;ReorderArray reorderArray = new ReorderArray();// 只有一个元素数组int[] arr1 = {1};int[] result1 = {1};reorderArray.reorderArray(arr1);flag &= reorderArray.equal(arr1, result1);// 全奇数数组int[] arr2 = {1, 1, 1, 1};int[] result2 = {1, 1, 1, 1};reorderArray.reorderArray(arr2);flag &= reorderArray.equal(arr2, result2);// 全偶数数组int[] arr3 = {8, 8, 8};int[] result3 = {8, 8, 8};reorderArray.reorderArray(arr3);flag &= reorderArray.equal(arr3, result3);// 既有奇数也有偶数int[] arr4 = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};int[] result4 = {1, 9, 3, 7, 5, 6, 4, 8, 2, 10};reorderArray.reorderArray(arr4);flag &= reorderArray.equal(arr4, result4);// 输入空数组boolean tryFlag = false;try {reorderArray.reorderArray(null);} catch (NullPointerException e) {tryFlag = true;} finally {// 跑出异常才对flag = tryFlag;}System.out.println(flag);}}

参考资料：

《剑指offer》  面试题14