Daily Coding Problem
https://www.dailycodingproblem.com/
这个是朋友拿这里的题问我然后我就顺便订阅了，大概操作是每天发一道面试题给你。
看了一下之后打算每天就算强迫自己做一道题吧……就开了个Git库记录。
https://github.com/Birdy-C/DailyCodingProblem
但是发现很多都是leetcode上有的，所以很多直接附leetcode链接了。
github上更新的应该会快一点。
文章目录
1 [Eazy]
This problem was recently asked by Google.
Given a list of numbers and a number k, return whether any two numbers from the list add up to k.
For example, given [10, 15, 3, 7] and k of 17, return true since 10 + 7 is 17.
Bonus: Can you do this in one pass?
HINT. https://leetcode.com/problems/two-sum/
2 [Hard]
This problem was asked by Uber.
Given an array of integers, return a new array such that each element at index i of the new array is the product of all the numbers in the original array except the one at i.
For example, if our input was [1, 2, 3, 4, 5], the expected output would be [120, 60, 40, 30, 24]. If our input was [3, 2, 1], the expected output would be [2, 3, 6].
HINT. https://leetcode.com/problems/product-of-array-except-self/
3 [Medium]
This problem was asked by Google.
Given the root to a binary tree, implement serialize(root), which serializes the tree into a string, and deserialize(s), which deserializes the string back into the tree.
For example, given the following Node class
class Node:
def __init__(self, val, left=None, right=None):
self.val = val
self.left = left
self.right = right
The following test should pass:
node = Node('root', Node('left', Node('left.left')), Node('right'))
assert deserialize(serialize(node)).left.left.val == 'left.left'
HINT. https://leetcode.com/problems/serialize-and-deserialize-binary-tree/
If val could be any string that contains spaces or other special characters, some extra job should be done to encode and decode it, e.g. how the C do with character ‘/’.
4 [Hard]
This problem was asked by Stripe.
Given an array of integers, find the first missing positive integer in linear time and constant space. In other words, find the lowest positive integer that does not exist in the array. The array can contain duplicates and negative numbers as well.
For example, the input [3, 4, -1, 1] should give 2. The input [1, 2, 0]should give 3.
You can modify the input array in-place.
HINT. https://leetcode.com/problems/first-missing-positive/