二分查找的递归和非递归实现

来源：互联网发布：tornado和nginx 编辑：程序博客网时间：2024/05/21 10:22
public class BinarySearch {    //非递归    public static int binSearch1(int[] arr, int target) {        if(arr == null || arr.length == 0)            return -1;        int left = 0, right = arr.length - 1;        while(left <= right) {            int mid = (left + right) / 2;            if(arr[mid] == target) {                return mid;            }            if(arr[mid] < target) {                left = mid + 1;            }            if(arr[mid] > target) {                right = mid - 1;            }        }        return -1;    }    //递归    public static int binSearch2(int[] arr, int target, int left, int right) {        if(arr == null || arr.length == 0)            return -1;        if(left > right) {            return -1;        }        int mid = (left + right) / 2;        if(arr[mid] == target) {            return mid;        }        if(arr[mid] > target) {            return binSearch2(arr, target, left, mid-1);        }        if(arr[mid] < target) {            return binSearch2(arr, target, mid+1, right);        }        return -1;    }    public static void main(String[] args) {        int[] testArr = new int[]{1,2,3,5,8,9,12,13,15,20};        System.out.println(binSearch1(testArr, 3));        System.out.println(binSearch2(testArr, 3, 0, 10));    }}
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