LeetCode 35. Search Insert Position Java

原创于 2018-05-14 13:06:11 发布 · 296 阅读

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本文介绍了一种在已排序数组中查找目标值插入位置的算法。通过二分查找的方法确定目标值应该插入的位置，适用于没有重复元素的情况。文章提供了详细的算法实现过程及四个示例说明。

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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.

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

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class Solution {
   public int searchInsert(int[] nums, int target) {
        int n = nums.length;
        int lo = 0, hi = n-1;
        int mid = 0;
        while(lo < hi){
            mid = (lo+hi)/2;
            if(target == nums[mid]){
                return mid;
            }
            else if(target < nums[mid]){
                hi = mid-1;
            }
            else{
                lo = mid+1;
            }
        }
        if(lo == hi){
            if(target > nums[hi]){
                return hi+1;
            }
            else{
                return hi;
            }
        }
        return mid;
    }
}