leetcode-41-First Missing Positive

最新推荐文章于 2020-06-02 21:01:39 发布

zem_nezer

最新推荐文章于 2020-06-02 21:01:39 发布

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本文探讨了在处理数组操作问题时，如何通过使用Map数据结构将时间复杂度从O(nlogn)降低到O(n)，并介绍了这种方法在解决类似问题时的应用价值。通过将数组映射到Map中，实现了一种重新分配过程，将未排序结构转换为有序结构，从而高效地解决了特定问题。

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Base on the idea:
With the length of the array l, we can know that the result will be range from[1, l + 1]. E.g. Now we have array[1, 2, 3], the result will be 4, if array = [5, 4, 7], the result will be 1

So, we have use map to map our vector/array to the map, then you can imagine it is a reallocate process, which a weakly map a unsort struct to sotred struct.

Intuition:
At first I think we can sort the array then go through it, the time complexity is O(nlogn). So we need to use someway to decrease to O(n). Because we do not need to do anything with the array itself, we can use a map to store the array.

I think it is a very useful method when deal with other problem like this, which is not directly manipulate with array but need to use it.

Error:
N/A