31 - Search Insert Position

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本文介绍了一种基于二分查找的算法实现，该算法用于在一个已排序的数组中查找目标值，并返回目标值的位置索引；如果未找到，则返回目标值应当插入的位置索引。文章提供了详细的代码实现和注释，帮助读者理解算法的工作原理。

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

solution: 还是二分查找，返回找到的索引，若没找到则返回较小的索引值。

ps：提交后发现，出循环之后还需要加一句判定，比如{1}，2的情况，应该返回start+1而不是start的。

class Solution {
public:
    int searchInsert(int A[], int n, int target) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(A == NULL || n <= 0)
            return 0;
        
        int start = 0;
        int end = n - 1;
        while(start < end)
        {
            int mid = start + (end - start) / 2;
            if(A[mid] == target)
                return mid;
            
            if(A[mid] < target)
                start = mid + 1;
            else
                end = mid -1;
        }
        if(A[start] < target)
            return start +1;
        return start;
        
    }
};