景兄弟手撕算法之二分查找(不重複的序列)

package find;

public class SimpleBinarySearch {
    /**
     * 數據元素不重複情況下的二分查找
     * @param args
     */
    public static void main(String[] args) {
        int arr[] = new int[]{11,8,3,9,7,1,2,5};
        System.out.println("binarySearch "+binarySearch(arr,9));
        System.out.println("binarySearch2 "+binarySearch2(arr,9,0,arr.length-1));
    }

    /**
     * 使用循環實現
     * @param array
     * @param value
     * @return
     */
    public static int binarySearch(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;
    }

    /**
     * 使用遞歸實現
     * @param array
     * @param value
     * @return
     */
    public static int binarySearch2(int[] array,int value,int low,int high) {
        if (low >= high) {
            return -1;
        }
        int mid = (low + high) / 2;
        if (array[mid] == value) {
            return mid;
        } else if (array[mid] > value) {
            return binarySearch2(array, value, mid + 1, high);
        } else {
            return binarySearch2(array, value, low, mid - 1);
        }
    }
}