二分查找，数组去重Java

/**
* 二分查找
*/
package algorithms;

/**
* @author
*
* @time 2017年5月9日 下午3:48:29
*/
public class BinarySearch {

public static int rank(int key, int[] a){
//数组必须是有序的
int head = 0;
int tail = a.length - 1;
while(head <= tail){
//被查找的键要么不存在，要么必然存在于a[head..tail]之中
int mid = head + (tail - head)/2;
if(key < a[mid]){
tail = mid - 1;
}else if(key > a[mid]){
head = mid + 1;
}else{
return mid;
}
}
return -1;
}

//递归法
public static int binarySearch(int[] a,int head,int tail,int key){
//数组必须是有序的
//        int head = 0;
//        int tail = a.length - 1;
if(head <= tail){
//被查找的键要么不存在，要么必然存在于a[head..tail]之中
int mid = head + (tail - head)/2;
if(key < a[mid]){
tail = mid - 1;
}else if(key > a[mid]){
head = mid + 1;
}else{//key == a[mid]
return mid;
}
return binarySearch(a,head,tail,key);
}
return -1;
}

public static void main(String[] args) {
//        int[] a = {10,20,30,40,50,60};
//        int i = rank(40,a);
//        System.out.println(i);
//        if(i>-1){
//            System.out.println(a[i]);
//        }
//        System.out.println(binarySearch(a,0,a.length-1,40));
int[] a = {10,20,30,30,30,40,40,40,40,50,60};
int[] b = duplicateRemoval(a);//去重后的数组
}
/**
* 数组去重
*/
private static int[] duplicateRemoval(int[] a) {
//
int num = count(a);
int[] b = new int[a.length-num];
int count = 0;
b[0] = a[0];
for(int i = 0;i < a.length-1;i++){
if(a[i]==a[i+1]){
count ++;
}else{
b[i+1-count] = a[i+1];
}
}
return b;

}
/**
* 计算重复数量
*/
private static int count(int[] a) {
int count = 0;
for(int i = 0;i < a.length-1;i++){
if(a[i]==a[i+1]){
count ++;
}
}
return count;

}
}