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34 lines
1.1 KiB
Java
34 lines
1.1 KiB
Java
package com.jwetherell.algorithms.search;
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/**
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* Lower bound search algorithm.
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* Lower bound is kind of binary search algorithm but:
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* -If searched element doesn't exist function returns index of first element which is bigger than searched value.
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* -If searched element is bigger than any array element function returns first index after last element.
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* -If searched element is lower than any array element function returns index of first element.
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* -If there are many values equals searched value function returns first occurrence.
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* Behaviour for unsorted arrays is unspecified.
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* Complexity O(log n).
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*
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* @author Bartlomiej Drozd <mail@bartlomiejdrozd.pl>
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* @author Justin Wetherell <phishman3579@gmail.com>
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*/
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public class LowerBound {
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private LowerBound() { }
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public static int lowerBound(int[] array, int length, int value) {
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int low = 0;
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int high = length;
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while (low < high) {
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final int mid = (low + high) / 2;
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if (value <= array[mid]) {
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high = mid;
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} else {
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low = mid + 1;
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}
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}
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return low;
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}
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}
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