Java实现二分查找(递归与非递归)

    前提条件：使用二分查找的数组必须是有序的。

public class BinarySearch {  
  
    public static void main(String[] args) {  
        int[] array = new int[] { 1, 2, 3, 4, 5, 6, 7, 9, 10 };  
        System.out.println(search1(array, 0, array.length - 1, 10));  
        System.out.println(search2(array, 10));  
    }  
  
    /** 
     * 递归写法 
     * 
     * @param array 
     * @param low 
     * @param high 
     * @param value 
     * @return int 
     */  
    public static int search1(int[] array, int low, int high, int value) {  
        int mid = (low + high) / 2;  
        if (array[mid] == value) {  
            return mid;  
        } else if (array[mid] < value) {  
            return search1(array, mid + 1, high, value);  
        } else {  
            return search1(array, 0, mid - 1, value);  
        }  
    }  
  
    /** 
     * 非递归写法 
     * 
     * @param array 
     * @param value 
     * @return int 
     */  
    public static int search2(int[] array, int value) {  
        int low = 0;  
        int high = array.length - 1;  
  
        while (low <= high) {  
            int mid = (low + high) / 2;  
            if (array[mid] == value) {  
                return mid;  
            } else if (array[mid] < value) {  
                low = mid + 1;  
            } else {  
                high = mid - 1;  
            }  
        }  
        return -1;  
    }  
}