https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/ Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. Code # Definition for a binary tree node. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution(object): def …
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For normal list in Python, slicing copies the references without copying underlying contents. (See the fact that`id(a[1])` and `id(b[0])` are identical below.) >>> a = [1,2,3] >>> b = a[1:3] >>> a [1, 2, 3] >>> b [2, 3] >>> id(a[1]) 25231680 >>> id(b[0]) 25231680 >>> b[0] = 999 >>> a [1, 2, 3] >>> …
https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/ Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete at most two transactions. Note:You may not engage in multiple transactions at the same time (ie, you must sell the stock before you …
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https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/ Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times). However, you may not engage …
Continue reading “Leetcode 122: Best Time to Buy and Sell Stock II”
https://leetcode.com/problems/best-time-to-buy-and-sell-stock/ Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit. Code import sys class …
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This topic has been in my wish list for a long time. I will try to articulate my understanding of eigenvector and eigenvalue after digestion informative materials from different sources. First of all, we can consider multiplication between a square matrix and a vector as a transformation of such that is rotated and scaled. By …
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https://leetcode.com/problems/minimum-depth-of-binary-tree/ Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. Code # Definition for a binary tree node. # class TreeNode(object): # def __init__(self, x): # self.val = x # self.left = None …
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https://leetcode.com/problems/largest-number/ Given a list of non negative integers, arrange them such that they form the largest number. For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330. Note: The result may be very large, so you need to return a string instead of an integer. Code class Solution(object): def largestNumber(self, …
https://leetcode.com/problems/path-sum-ii/ Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ …
https://leetcode.com/problems/path-sum-ii/ Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum. For example: Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] …