LeetCode——Search Insert Position

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.

• Example 1:
  Input: [1,3,5,6], 5
  Output: 2
• Example 2:
  Input: [1,3,5,6], 2
  Output: 1
• Example 3:
  Input: [1,3,5,6], 7
  Output: 4
• Example 4:
  Input: [1,3,5,6], 0
  Output: 0

解法一

public int searchInsert(int[] nums, int target) {
        if(nums==null||nums.length==0||target<nums[0])
        	return 0;
        int length=nums.length;
        for(int i=0;i<length;i++)
        {
        	if(target<=nums[i])
        		return i;
        }
        return length;
    }

Runtime: 2 ms, faster than 100.00% of Java online submissions for Search Insert Position.
Memory Usage: 39.5 MB, less than 14.13% of Java online submissions for Search Insert Position.

解法二——利用二分搜索法

数组较大的话用二分法可能更快一点

public int searchInsert1(int[] nums, int target) {
		if(nums==null||nums.length==0||target<nums[0])
        	return 0;
		int length=nums.length;
		if(nums[length-1]<target)
			return length;
		int start=0,end=nums.length-1;
		while(start<end)
		{
			int mid=(start+end)/2;
			if(nums[mid]==target)
				return mid;
			else if(nums[mid]<target)
				start=mid+1;
			else
				end=mid;
		}
		return end;
	}

Runtime: 2 ms, faster than 100.00% of Java online submissions for Search Insert Position.
Memory Usage: 39.4 MB, less than 22.91% of Java online submissions for Search Insert Position.