/* * The MIT License * * Copyright 2012 Abhijit Gaikwad <gaikwad.abhijit@gmail.com>. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ /** * * @author Abhijit Gaikwad <gaikwad.abhijit@gmail.com> visit http://gabhi.com */ package com.gabhi.search; /** * * @author Abhijit Gaikwad <gaikwad.abhijit@gmail.com> */ //Implement Binary Search /** * A straightforward implementation of binary search is recursive. The initial * call uses the indices of the entire array to be searched. The procedure then * calculates an index midway between the two indices, determines which of the * two subarrays to search, and then does a recursive call to search that * subarray. Each of the calls is tail recursive, so a compiler need not make a * new stack frame for each call. The variables imin and imax are the lowest and * highest inclusive indices that are searched. * */ public class BinarySearch { public static final int NOT_FOUND = -1; public static void main(String[] args) { int SIZE = 8; Comparable[] a = new Integer[SIZE]; for (int i = 0; i < SIZE; i++) { a[ i] = new Integer(i * 2); } for (int i = 0; i < SIZE * 2; i++) { System.out.println("Found " + i + " at " + binarySearch(a, new Integer(i))); } } public static int binarySearch(Comparable[] a, Comparable x) { int low = 0; int high = a.length - 1; int mid; while (low <= high) { mid = (low + high) / 2; if (a[ mid].compareTo(x) < 0) { low = mid + 1; } else if (a[ mid].compareTo(x) > 0) { high = mid - 1; } else { return mid; } } return NOT_FOUND; // NOT_FOUND = -1 } }

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