Java二分查找實現(xiàn),歡迎大家提出交流意見.
/**
*名稱:BinarySearch
*功能:實現(xiàn)了折半查找(二分查找)的遞歸和非遞歸算法.
*說明:
*???? 1、要求所查找的數(shù)組已有序,并且其中元素已實現(xiàn)Comparable<T>接口,如Integer、String等.
*????2、非遞歸查找使用search();,遞歸查找使用searchRecursively();
*
*本程序僅供編程學(xué)習(xí)參考
*
*@author:?? Winty
*@date:???? 2008-8-11
*@email:????[email]wintys@gmail.com[/email]
*/

class BinarySearch<T extends Comparable<T>> {
????private T[]??data;//要排序的數(shù)據(jù)

????public BinarySearch(T[] data){
????????this.data = data;
????}

????public int search(T key){
????????int low;
????????int high;
????????int mid;

????????if(data == null)
????????????return -1;

????????low = 0;
????????high = data.length - 1;

????????while(low <= high){
????????????mid = (low + high) / 2;
????????????System.out.println("mid " + mid + " mid value:" + data[mid]);///
????????????
????????????if(key.compareTo(data[mid]) < 0){
????????????????high = mid - 1;
????????????}else if(key.compareTo(data[mid]) > 0){
????????????????low = mid + 1;
????????????}else if(key.compareTo(data[mid]) == 0){
????????????????return mid;
????????????}
????????}

????????return -1;
????}

????private int doSearchRecursively(int low , int high , T key){
????????int mid;
????????int result;

????????if(low <= high){
????????????mid = (low + high) / 2;
????????????result = key.compareTo(data[mid]);
????????????System.out.println("mid " + mid + " mid value:" + data[mid]);///
????????????
????????????if(result < 0){
????????????????return doSearchRecursively(low , mid - 1 , key);
????????????}else if(result > 0){
????????????????return doSearchRecursively(mid + 1 , high , key);
????????????}else if(result == 0){
????????????????return mid;
????????????}
????????}
????????
????????return -1;
????}

????public int searchRecursively(T key){
????????if(data ==null)return -1;

????????return doSearchRecursively(0 , data.length - 1 , key);
????}

????public static void main(String[] args){
????????Integer[] data = {1 ,4 ,5 ,8 ,15 ,33 ,48 ,77 ,96};
????????BinarySearch<Integer> binSearch = new BinarySearch<Integer>(data);
????????//System.out.println("Key index:" + binSearch.search(33) );

????????System.out.println("Key index:" + binSearch.searchRecursively(3) );

????????//String [] dataStr = {"A" ,"C" ,"F" ,"J" ,"L" ,"N" ,"T"};
????????//BinarySearch<String> binSearch = new BinarySearch<String>(dataStr);
????????//System.out.println("Key index:" + binSearch.search("A") );
????}
}

轉(zhuǎn)載于:https://blog.51cto.com/wintys/94051

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