此博客介绍了Java中的上界搜索算法。它是一种二分搜索算法，返回首个大于搜索值的元素索引，若搜索元素比数组所有元素都大，则返回数组最后元素后的首个索引，复杂度为O(log n)，还给出了算法实现代码。
/**
*
*
*
Copyright 1994-2018 JasonInternational
*
All rights reserved.
*
Created on 2018年4月10日 上午9:46:32
*
Created by Jason
*
*
*/
package cn.ucaner.algorithm.search;
/**
* Upper bound search algorithm.
* Upper bound is kind of binary search algorithm but:
* -It returns index of first element which is grater than searched value.
* -If searched element is bigger than any array element function returns first index after last element.
*
* Behaviour for unsorted arrays is unspecified.
*
* Complexity O(log n).
*
* @author Bartlomiej Drozd
* @author Justin Wetherell
*/
public class UpperBound {
private UpperBound() { }
public static int upperBound(int[] array, int length, int value) {
int low = 0;
int high = length;
while (low < high) {
final int mid = (low + high) / 2;
if (value >= array[mid]) {
low = mid + 1;
} else {
high = mid;
}
}
return low;
}
}
扫一扫
1764
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
