题目Search Insert Position
英文描述: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.
中文描述:给定一个排序数组和一个目标值,在数组中找到目标值,并返回其索引。如果目标值不存在于数组中,返回它将会被按顺序插入的位置。
你可以假设数组中无重复元素。
示例: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

来源:力扣

分析:根据题目意思,明显可以用二分查找算法,直接走代码吧!
Java:


    /** * 二分查找算法解题 * @param arr * @param target * @return */
    public static int searchInsert(int[] arr,int target){
   
        int left = 0;
        int right = arr.length;
        while (left<right){
   
            int mid = left+(right-left)/2;
            if (arr[mid]<target) left= mid+1;
            else right = mid;
        }
        return left;
    }

C++:

    int searchInsert(vector<int>& nums, int target) {
   
       int left = 0,right = nums.size();
       while(left<right){
   
           int mid = left+(right-left)/2;
           nums[mid]<target?left = mid+1:right=mid;
       } 
       return left;
    }

复杂度:时间复杂度O(logn)
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