局部最小值问题：在一个相邻位置的数不相等的数组中寻找任意一个局部最小值

public class BSAwesome {
    public static int getLessIndex(int[] arr){
        if (arr==null || arr.length ==0){
            return -1;
        }
        if (arr[0] < arr[1]){
            return 0;
        }
        if (arr[arr.length-1] < arr[arr.length-2]){
            return arr.length-1;
        }
        int left = 1;
        int right = arr.length - 2;
        int mid = 0;
        while (left < right){
            mid = (left + right) / 2;
            if (arr[mid] > arr[mid - 1]){
                right = mid - 1;
            }else if (arr[mid] > arr[mid + 1]){
                left = mid + 1;
            }else
                return mid;
        }
        return left;
    }

    public static void main(String[] args) {
        int[] arr = {1,0,3,5,6,8};
        System.out.println("数组中某一个局部最小值的位置："+ getLessIndex(arr));
    }
}

 

用例运行结果：