Java InterpolationSearch
/**
* <html>
* <body>
* <P> Copyright 1994-2018 JasonInternational </p>
* <p> All rights reserved.</p>
* <p> Created on 2018年4月10日 上午9:46:32</p>
* <p> Created by Jason</p>
* </body>
* </html>
*/
package cn.ucaner.algorithm.search;
/**
* Interpolation search is an algorithm for searching for a given key in an indexed array that has been ordered by numerical values assigned to the keys (key values). It parallels how humans search
* through a telephone book for a particular name, the key value by which the book's entries are ordered.
* <p>
* Worst-case performance O(n)<br>
* Average performance O(log(log(n)))<br>
* <p>
* @see <a href="https://en.wikipedia.org/wiki/Interpolation_search">Interpolation Search (Wikipedia)</a>
* <br>
* @author Justin Wetherell <phishman3579@gmail.com>
*/
public class InterpolationSearch {
private static int[] sorted = null;
// Assuming the array is sorted
public static final int find(int value, int[] array) {
InterpolationSearch.sorted = array;
try {
return recursiveFind(value, 0, InterpolationSearch.sorted.length - 1);
} finally {
InterpolationSearch.sorted = null;
}
}
private static int recursiveFind(int value, int start, int end) {
if (start == end) {
int lastValue = sorted[start]; // start==end
if (value == lastValue)
return start; // start==end
return Integer.MAX_VALUE;
}
final int mid = start + ((value - sorted[start]) * (end - start)) / (sorted[end] - sorted[start]);
if (mid < 0 || mid > end)
return Integer.MAX_VALUE;
int midValue = sorted[mid];
if (value == midValue)
return mid;
if (value > midValue)
return recursiveFind(value, mid + 1, end);
return recursiveFind(value, start, mid - 1);
}
}