Leetcode[java] 35. Search Insert Position

最新推荐文章于 2022-04-06 16:49:21 发布

原创最新推荐文章于 2022-04-06 16:49:21 发布 · 228 阅读

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本文介绍了一个查找并返回目标值在已排序数组中应插入位置的算法。该算法首先判断目标值与数组首尾元素的关系，然后使用二分搜索确定具体插入位置。适用于没有重复元素的情况。

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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

public class Solution {
    public int searchInsert(int[] nums, int target) {
	        int res=-1;
	        int len = nums.length;
	        if(nums==null||len==0)
	            return 0;
	        if(target<=nums[0])
	            return 0;
	        else if(target>nums[len-1])
	            return len;
	        return binarySearch(target,nums,0,len-1);
	    }
	     private int binarySearch(int target,int[] nums, int begin, int end){
            if(begin+1==end){
	        	if(target<=nums[begin]){
	                return begin;
	            }
	            else if(target<=nums[end]){
	                return begin+1;
	            }
	        }
	            
	        int mid = begin + (end-begin)/2;
	        System.out.println(mid);
	        if(target>nums[mid]){
	            
	            return binarySearch(target,nums,mid,end);
	        } else if(target<nums[mid]){
	            
	            return binarySearch(target,nums,begin,mid);
	        } else{
	            return mid;
	        }
	            
	    }
}