斐波那契查找算法 (java)

 
 
import java.util.Arrays;
 
public class FibonacciSearch {
    public static void main(String[] args) {
        int[] arr = {1, 8, 10, 89, 1000, 1234};
        int[] fib = fib(20);
        System.out.println(Arrays.toString(fib));
        System.out.println(fibSearch(arr,1234));
    }
 
    /**
     * 获取斐波那契数列
     */
    public static int[] fib(int size) {
        int[] arr = new int[size];
        for (int i = 0; i < size; i++) {
            if (i == 1 || i == 0) {
                arr[i] = 1;
            } else {
                arr[i] = arr[i - 1] + arr[i - 2];
            }
        }
        return arr;
    }
 
    /**
     * 斐波那契查找算法
     *
     * @param arr 数组
     * @param key 查找的值
     * @return 返回对相应下标，默认返回-1；
     */
    public static int fibSearch(int[] arr, int key) {
        int low = 0;
        int hight = arr.length - 1;
        //斐波那契数组的下标
        int k = 0;
        //存放mid值
        int mid = 0;
        int[] fibArr = fib(arr.length);
        //获取斐波那契分割数值的下标
        while (hight > fibArr[k] - 1) {
            k++;
        }
        //fibArr[k]的值可能大于a的长度，需要扩充，新增的值用原数组最大值
        int[] temp = Arrays.copyOf(arr, fibArr[k]);
        for (int i = arr.length; i < fibArr[k]; i++) {
            temp[i] = arr[arr.length - 1];
        }
        //使用while寻找key
        while (low <= hight) {
            mid = low + fibArr[k - 1] - 1;
            //fibArr[k]=fibArr[k-1]+fibArr[k-2];
            //全部元素=前边的元素+后边的元素
            //前边k-1 后边k-2
            if (key < temp[mid]) {
                hight = mid - 1;
                k--;
            }else if(key>temp[mid]){
                low=mid+1;
                k-=2;
            }else{
                if(mid>hight){
                    return hight;
                }else{
                    return mid;
                }
            }
        }
        return -1;
    }
}