LeetCode Search Insert Position

最新推荐文章于 2025-08-08 21:26:37 发布

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本文介绍了一种使用二分搜索法解决特定问题的方法。给定一个已排序的数组及一个目标值，通过二分搜索法找到目标值在数组中的位置，若不存在则返回其应该插入的位置。文章提供了详细的算法实现过程。

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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

思路:运用二分搜索法，然后就是根据不同的情况来进行判断：如果找目标值返回响应下标值，如果当middle<target且middle+ 1>target

代码如下：

class Solution {
public:
    int searchInsert(vector<int>& nums, int target) {
        int front,back,middle;
        front =0;back=nums.size()-1;
        middle = (front+back)/2;
        while(front <= back)
        {
            if(nums[middle] < target)
            {
                if(middle < nums.size()-1 && nums[middle+1] > target)
                    return middle+1;
                front = middle+1;
                middle = (front+back)/2;
            }
            else if(nums[middle] > target)
            {
                if(middle > 0 && nums[middle-1] < target)
                    return middle;
                back = middle-1;
                middle = (front+back)/2;
            }
            else
                return middle;
        }
        
        if(nums[middle] < target)
            return middle+1;
        else
            return middle;
    }
};