Java 二分法查找

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使用二分法进行查找，程序如下：

package cn.com.yy;import java.util.Arrays;/** * 二分法查找 * @author Administrator * */public class BinarySearchClient {public static void main(String[] args) {int[] arr = new int[]{4,5,2,1,8,3,0};Arrays.sort(arr); //数组进行排序int result = 4;int index = binarySearch(arr,result);System.out.println(index); //排序后的数组下标 4}/** *  * @param arr * @param result * @return 返回排序后的数组下标 *  */public static int binarySearch(int[] arr, int result){int beginIndex = 0; //开始索引int endIndex = arr.length - 1; //结束索引int middleIndex = -1;    //默认的目标索引if(arr.length <1)return -1;if(result < arr[beginIndex] || result > arr[endIndex] || beginIndex > endIndex)return -1;while(beginIndex <= endIndex){middleIndex = (beginIndex + endIndex) >>> 1; //右移位运算符if(result < arr[middleIndex]){endIndex = middleIndex -1;}else if(result > arr[middleIndex]){beginIndex = middleIndex + 1;}else{return middleIndex ;}}return -1;}}

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