旋转数组查找， 二分查找的递归于非递归实现

package java_study.JianZhiOffer;import org.junit.Test;import java.util.Arrays;/** * Created by ethan on 2015/6/22. * 剑指offer 第八题 旋转数组查找 * 查找算法中重要的：二分，hash，二叉搜索树 * 排序中重要的算法：快排的partition思路（一次可以定位一个值）， 堆排序（选出最小的or最大的几个）， 归并排序（n个有序子序列） * 插入排序：保证前n位是有序的， 希尔排序：间隔有序子序列， 冒泡排序： 能挑出最大or最小的几位数放到最后，但是效率比堆排序低， 选择排序：找出最大or最小放在最前or最后 */public class No8RotateTheMini {    // 原始的二分查找    public boolean binaryFind(int[] arr, int goal){        return binaryFindImpl(arr, goal, 0, arr.length-1);    }    // 递归实现    public boolean binaryFindImpl(int[] arr, int goal, int first, int last){        if (arr==null) return false;        if (first<0 || last<0 || first>last) return false;        int mid = (first+last)/2;        if (arr[mid]==goal) return true;        else if (arr[mid]<goal) return binaryFindImpl(arr, goal, mid + 1, last);        else return binaryFindImpl(arr, goal, first, mid - 1);    }    // 非递归实现    public boolean binaryFindNoRecursive(int[] arr, int goal){        if (arr==null) return false;        int first = 0;        int end = arr.length-1;        while (first<=end){            int mid = (first+end)/2;            if (arr[mid]==goal)                return true;            else if(arr[mid] < goal)                first = mid+1;            else                end = mid-1;        }        return false;    }    // 对于旋转数组    public int binaryFindRotation(int[] arr, int goal){        return binaryFindRotationInpl(arr, goal, 0, arr.length-1);    }    public int binaryFindRotationInpl(int[] arr, int goal, int first, int end){        if (arr==null) return -1;        if (first<0 || end<0 || first>end) return -1;        int mid = (first+end)/2;        if (arr[mid] == goal) return mid;        else {            if (arr[mid] > arr[first]){                if (arr[mid]>goal && arr[first]<=goal) return binaryFindRotationInpl(arr, goal, first, mid - 1);                else return binaryFindRotationInpl(arr, goal, mid+1, end);            }else {                if (arr[mid]<goal && arr[end]>=goal) return binaryFindRotationInpl(arr, goal, mid+1, end);                else return binaryFindRotationInpl(arr, goal, first, mid-1);            }        }    }    // 旋转数组找出最小的数    public int findRotationSortedArray(int[] arr){        return findRotationSortedArrayImpl(arr,  0, arr.length-1);    }    public int findRotationSortedArrayImpl(int[] arr, int first, int last){        if (arr==null || first<0 || last<0 || first>last) return -1;        if (last-first==1)            return last;        int mid = (first+last)/2;        if (arr[first] < arr[mid]) return findRotationSortedArrayImpl(arr,  mid, last);        else return findRotationSortedArrayImpl(arr, first, mid);    }    @Test    public void test(){        int[] arr = {23, 22, 81, 33, 67, 54, 92, 10, 3};        Arrays.sort(arr);        System.out.println(binaryFind(arr, 81));        System.out.println(binaryFindNoRecursive(arr, 81));        int[] arr1 = {10, 29, 32, 35, 42, 50, -1, 1, 5, 8, 9};        System.out.println(binaryFindRotation(arr1, 31));        System.out.println(findRotationSortedArray(arr1));    }}