二分查找及其变种大全（java版）

package search;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/** 
* @author  mengwen  E-mail:  [email protected]
* @date 创建时间：2016年12月14日 下午2:10:11 
* @version 1.0 
* @parameter  
* @since  
* @return  
*/
public class Search {
    public static final int[] data = new int[] {0,1,2,5,8,8,9,12,22,23,25,25,25,25,30,33,34,45,54,56,76,80,89,90,200,333};
    
    public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
        Class search = Class.forName("search.Search");
        Method[] methods = search.getDeclaredMethods();
        int num =25;
        int result =-1;
        System.out.println("需要二分查找的数字是"+num);
        for (Method method : methods) {
            if(method.getName()!="main"){
                result = (int) method.invoke(null,new Object[]{data,num});
                if(result!=-1){
                    System.out.println(method.getName()+" 方法找到该数字坐标为: "+result+"  验证数字： "+data[result]);
                }else{
                    System.out.println(method.getName()+" 方法未找到该数字 ");
                }
            }
        }
    }
    
    //普通二分查找
    static int binarySerach(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;

        // 这里必须是 <=
        while (left <= right) {
            int mid = (left + right) / 2;
            if (array[mid] == key) {
                return mid;
            }
            else if (array[mid] < key) {
                left = mid + 1;
            }
            else {
                right = mid - 1;
            }
        }

        return -1;
    }
    
    // 查找第一个相等的元素
    static int findFirstEqual(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;

        // 这里必须是 <=
        while (left <= right) {
            int mid = (left + right) / 2;
            if (array[mid] >= key) {
                right = mid - 1;
            }
            else {
                left = mid + 1;
            }
        }
        if (left < array.length && array[left] == key) {
            return left;
        }
        
        return -1;
    }
    // 查找最后一个相等的元素
    static int findLastEqual(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;

        // 这里必须是 <=
        while (left <= right) {
            int mid = (left + right) / 2;
            if (array[mid] <= key) {
                left = mid + 1;
            }
            else {
                right = mid - 1;
            }
        }
        if (right >= 0 && array[right] == key) {
            return right;
        }

        return -1;
    }
    
    // 查找最后一个等于或者小于key的元素
    static int findLastEqualSmaller(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;

        // 这里必须是 <=
        while (left <= right) {
            int mid = (left + right) / 2;
            if (array[mid] > key) {
                right = mid - 1;
            }
            else {
                left = mid + 1;
            }
        }
        return right;
    }
    //查找最后一个小于key的元素
    static int findLastSmaller(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;

        // 这里必须是 <=
        while (left <= right) {
            int mid = (left + right) / 2;
            if (array[mid] >= key) {
                right = mid - 1;
            }
            else {
                left = mid + 1;
            }
        }
        return right;
    }
    
    // 查找第一个等于或者大于key的元素
    static int findFirstEqualLarger(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;

        // 这里必须是 <=
        while (left <= right) {
            int mid = (left + right) / 2;
            if (array[mid] >= key) {
                right = mid - 1;
            }
            else {
                left = mid + 1;
            }
        }
        return left;
    }
    
    // 查找第一个大于key的元素
    static int findFirstLarger(int[] array, int key) {
        int left = 0;
        int right = array.length - 1;

        // 这里必须是 <=
        while (left <= right) {
            int mid = (left + right) / 2;
            if (array[mid] > key) {
                right = mid - 1;
            }
            else {
                left = mid + 1;
            }
        }
        return left;
    }
}