com.github.dm.rf.android.utils.BinarySearch Maven / Gradle / Ivy
/**
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.github.dm.rf.android.utils;
/**
* Utility class implementing a binary search algorithm.
*
* Created by davide-maestroni on 3/27/14.
*/
public class BinarySearch {
/**
* Avoid direct instantiation.
*/
private BinarySearch() {
}
/**
* Checks if the specified array contains the passed values in the first count
* elements.
*
* Note that the elements in the array must be sorted previously to call this method, otherwise
* unexpected results will be generated.
*
* @param array the array to analyze.
* @param count the max number of elements to analyze.
* @param value the value to search for.
* @return whether the value has been found in the first count elements.
*/
public static boolean contains(final int[] array, final int count, final int value) {
// Re-implementing binary search since it is not available in API level 8
int parent = count;
int current = parent >> 1;
int match = array[current];
while (match != value) {
final int next;
if (value > match) {
next = current + ((parent - current) >> 1);
} else {
next = current >> 1;
parent = current;
}
if (next == current) {
return false;
}
current = next;
match = array[current];
}
return true;
}
}