Java-数据结构与算法-二分查找法

1.二分查找法思路：不断缩小范围，直到low <= high

2.代码：

package Test;

import java.util.Arrays;

public class BinarySearch {
    
    public static void main(String[] args) {
        int [] a = {1,5,7,9,11,12,16,20};
        int target = 16;
        //System.out.println(Arrays.binarySearch(a, target));
        System.out.println(binarySearch(a, target));
    }

    public static int binarySearch(int [] a, int target){
        int low = 0;
        int high = a.length - 1;

        while (low <= high) {
            int mid = (low + high) >>> 1;
            int midVal = a[mid];

            if (midVal < target)
                low = mid + 1;
            else if (midVal > target)
                high = mid - 1;
            else
                return mid; // key found
        }
        return -(low + 1);  // key not found.
    }
}

3.结果：6