斐波那契查找算法的实现(又称黄金分割查找法;【java语言实现】)
核心思想
由斐波那契数列 F[k]=F[k-1]+F[k-2] 的性质,可以得到 (F[k]-1)=(F[k-1]-1)+(F[k-2]-1)+1 。
该式说明:只要顺序表的长度为F[k]-1,则可以将该表分成长度为F[k-1]-1和F[k-2]-1的两段,从而中间位置为mid=low+F(k-1)-1
将mid作为顺序表的分割点
由于mid的确认过程不涉及除法,仅仅需要进行加或者减;理论上比二分查找法消耗要小,速度快
实现代码
package com.zhaojinlei.test;import java.util.Arrays;/** * className:FibonacciSearch * * @author:ZHAOJINLEI * @version:0.1 * @date:2020/9/517:17 * @since:jdk1.8 */public class FibonacciSearch { public static void main(String[] args) { //测试1 int[] ser = {0,3,5,9,12,13,26,66,99}; int index = search(ser, 26); System.out.println("{0,3,5,9,12,13,26,66,99}中查找26:"); System.out.println("index:"+index +" value:"+ser[index]); System.out.println(); //测试2 int[] ser1 = {0,3,5,9,12,13,26,66,99,109,110,112,116,225,336,995,1000,1001,1002,1030}; int index1 = search(ser1, 995); System.out.println("{0,3,5,9,12,13,26,66,99,109,110,112,116,225,336,995,1000,1001,1002,1030}中查找995:"); System.out.println("index:"+index1 +" value:"+ser1[index1]); } //创建一个含n个数的斐波那契数列 public static int[] createFibonacci(int n) { int[] ints = new int[n]; ints[0] = 1; ints[1] = 1; for (int i = 2; i < ints.length; i++) { ints[i] = ints[i - 1] + ints[i - 2]; } return ints; } public static int search(int ser[], int elem) { int n = 10; //初始斐波那契数列长度10 int[] fibs = createFibonacci(n); while (fibs[fibs.length - 1] < ser.length) {//斐波那契数列长度不够,进行扩容(每次扩2倍) n *= 2; fibs = createFibonacci(n); } int low = 0; int high = ser.length; int k = fibs.length - 1; int mid; while (fibs[k] - 1 > ser.length) {//找到符合要求的k的最小值 k--; } k++; int[] ints = Arrays.copyOf(ser,fibs[k]-1);//复制原数组 for (int i = ser.length; i < ints.length; i++) {//超出原数组的最大索引的位置填充原数组最大值 ints[i] = ser[ser.length - 1]; } while (low < high) { //检查两端 if(ints[low] == elem) return low; if(ints[high] == elem) return high; //黄金分割点 mid = low + fibs[k - 1]; if (ints[mid] == elem){ if(mid<ser.length-1){ return ser.length-1; }else { return mid; } } //低区查找 if(ints[mid]>elem){ high = mid-1; k--; } //高区查找 if(ints[mid]<elem){ low = mid+1; k-=2; } } return -1; }}