数组在排序数组中出现的次数

public static int getFirst(int[] data,int start,int end,int key)
	{
		if(data == null)return -2;
		if(start > end )
			return -1;
		
		int mid = ( start+end )/2;
		int midData = data[mid];
		
		if(midData == key)
		{
			if(( mid >0 && data[mid-1] !=key)|| mid==0)
				return mid;
			else 
				return getFirst(data, start, mid-1, key);//可以修改让其只返回一个return
				
		}else if(midData > key)
			
			return getFirst(data, start, mid-1, key);
		
		else 
			return getFirst(data, mid+1, end, key);
			
	}
	
	public static int getLast(int[] data,int start,int end,int key)
	{
		if(data == null)return -2;
		if(start > end)return -1;
		
		int mid = (start+end)/2;
		int midData = data[mid];
		
		if(midData == key)
		{
			if((  mid < data.length-1 && data[mid+1] !=key )|| mid == data.length-1 )
				return mid;
			else 
				return getLast(data, mid+1, end, key);
				
		}
		else if(midData > key)
			return  getLast(data, start, mid-1, key);
		else 
			return getLast(data, mid+1, end, key);
		
		
	}
	public static void getNumber(int[] data,int key)
	{
		int startIndex = getFirst(data, 0, data.length-1,key);
		int endIndex = getLast(data, 0, data.length-1,key);
		if(startIndex >-1 && endIndex > -1)
			System.out.println(endIndex-startIndex+1);
		else 
			System.out.println("no");
	}

版权声明：本文为博主原创文章，转载请注明出处。