leetcode_Search Insert Position

描述：

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Here are few examples.
[1,3,5,6], 5 → 2
[1,3,5,6], 2 → 1
[1,3,5,6], 7 → 4
[1,3,5,6], 0 → 0

思路：

1.变形的二分查找问题

2.最后A[mid]=target，index=mid

3.最后A[mid]!=target，又分A[mid]<target和A[mid]>target两种情况，

4.if(A[mid]<target),index=mid+1;if(A[mid]>target),index=mid;

代码：

public int searchInsert(int[] A, int target) {
		int len=A.length;
	    int start=0,end=len-1;
	    int mid=0;
	    int index=-1;//if A[mid]=target
	    int index2=-1;//if A[mid]!=target
	    while(start<=end)
	    {
	    	mid=(start+end)/2;
	    	if(A[mid]==target)
	    	{
	    		index=mid;
	    		break;
	    	}else if(A[mid]<target)
	    		start=mid+1;
	    	else 
	    		end=mid-1;
	    }
	    if(index!=-1)
	    	return index;
	    else
	    {
	    	if(A[mid]<target)
	    		index2=mid+1;
	    	else {
				index2=mid;
			}
	    }
	    return index2;
    }