基於有序陣列的二分查詢–java程式碼實現

有序陣列的java程式碼實現，其中有序陣列可能是兩段子有序陣列，如{7，9，2，4，5}：

程式碼塊

public class FindArrayIndexWithTarget {
    public static int find(int a[], int target)
    {
        if (null == a)
            return -1;
        int low, high;
        low = 0;
        high = a.length-1;

        int mid
 
 = 0;
        while(low < high)
        {
            mid = (low + high)/2;

            if (a[mid] > target)
            {
                if (a[low] > target)
                {
                    low = mid + 1;
                }
                else {
                    high = mid - 1;
                }
            }
            else
 
 if (a[mid] < target) {
                if (a[high] < target) {
                    high = mid - 1;
                } else {
                    low = mid + 1;
                }
            } else {
                return mid;
            }
        }
        if (a[low] == target)
            return
 
 low;

        return -1;
    }
}