随笔分类 - Level 3
摘要：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 comple
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摘要：Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional part is repeating
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摘要：The API: int read4(char *buf) reads 4 characters at a time from a file. The return value is the actual number of characters read. For example, it retu
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摘要：You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a conca
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摘要：Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n. For example:Given n = 13,Return
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摘要：Given a root node reference of a BST and a key, delete the node with the given key in the BST. Return the root node reference (possibly updated) of th
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摘要：Given a binary search tree and a node in it, find the in-order successor of that node in the BST. 1 public class Solution { 2 3 public TreeNode inorde
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摘要：Range Sum Query 2D - Mutable Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1)
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摘要：Two elements of a binary search tree (BST) are swapped by mistake. Recover the tree without changing its structure. Note: A solution using O(n) space
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摘要：Preorder: 因为是preorder traversal, 我们需要先print root，然后左节点，最后右节点，而且root左边子树一定比右边子树先print出来，所以，我们可以先把当前root的右节点压栈，然后把root的左节点压栈，这样每次从栈里取的时候，可以保证左边节点的root先取
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摘要：Factor Combinations Problem: Numbers can be regarded as product of its factors. For example, 8 = 2 x 2 x 2; = 2 x 4. Write a function that takes an in
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摘要：Given two sparse matrices A and B, return the result of AB. You may assume that A's column number is equal to B's row number. Example: A = [ [ 1, 0, 0
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摘要：Remove Duplicate Letters I Given a string which contains only lowercase letters, remove duplicate letters so that every letter appear once and only on
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摘要：One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record the node's value. If it is a null node,
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摘要：Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its ne
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摘要：Given two numbers represented as strings, return multiplication of the numbers as a string. Note: The numbers can be arbitrarily large and are non-neg
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摘要：Excel Sheet Column Title Given a positive integer, return its corresponding column title as appear in an Excel sheet. For example: Given a column titl
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摘要：Nested List Weight Sum I Given a nested list of integers, return the sum of all integers in the list weighted by their depth. Each element is either a
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摘要：Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and r
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摘要：Given a list of unique words. Find all pairs of distinct indices (i, j) in the given list, so that the concatenation of the two words, i.e.words[i] +
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