有序數組的二分查找---查找元素第一次和最後一次出現的位置及元素存儲

package searching;

public class BinSearch_ {

	/**
	 * binSearch：查找指定元素，并傳回所在數組中的位置
	 * InsertToArray：元素插入到有序數組，并擷取插入位置
	 * binSearchFirst：查找指定元素第一次出現的位置
	 * binSearchLast：查找指定元素最後一次出現的位置
	 */
	public static void main(String[] args) {
		int[] a={3,5,10,10,10,13,13,19,23};
		System.out.println(binSearch(a,23));	 	//8
		System.out.println(InsertToArray(a,1));		//0
		System.out.println(InsertToArray(a,4));		//1
		System.out.println("first:"+binSearchFirst(a,10));//2
		System.out.println("first:"+binSearchLast(a,10));//4
	}

	private static int binSearch(int[] a, int key) {
		// TODO Auto-generated method stub
		int min=0,max=a.length-1;
		int mid=(max+min)/2;
		while(min<=max){
			mid=(max+min)/2;
			if (key>a[mid]) {
				min=mid+1;
			}else if (key<a[mid]) {
				max=mid-1;
			}else {
				return mid;
			}
		}
		return -1;
	}

	private static int InsertToArray(int[] a, int key) {
		// TODO Auto-generated method stub
		int min=0,max=a.length-1;
		int mid=0;
		while(min<=max){
			mid=(max+min)/2;
			if (key>a[mid]) {
				min=mid+1;
			}else if (key<a[mid]) {
				max=mid-1;
			}else {
				return mid;
			}			
		}
		return min;
	}

	private static int binSearchFirst(int[] a, int key) {
		// TODO Auto-generated method stub
		int min=0,max=a.length-1;
		int mid=0;
		while(min<=max){
			mid=(max+min)/2;
			if (key>a[mid]) {
				min=mid+1;
			}else{
				max=mid;
			}
			if (max==min) {
				break;
			}
		}
		if (a[min]!=key) {//當查找元素不存在時，傳回-1
			return -1;
		}else {
			return min;
		}
	}

	private static int binSearchLast(int[] a, int key) {
		// TODO Auto-generated method stub
		int min=0,max=a.length-1;
		int mid=0;
		while(min<=max){
			mid=(max+min+1)/2;
			if (key>=a[mid]) {
				min=mid;
			}else {
				max=mid-1;
			}
			if (max==min) {
				break;
			}
		}
		if (a[max]!=key) {//當查找元素不存在時，傳回-1
			return -1;
		}else {
			return max;
		}
	}

}