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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 (i.e., buy one and sell one share of the stock), design an algorithm to find the maximum profit.Note that you cannot sell a stock before you buy one.Example 1:Input: [7,1,5,3,6,4] Output: 5 Explanation: Buy on day 2 (price = 1) and sell on day 5 (p.. 더보기
Missing Number Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.Example 1:Input: [3,0,1] Output: 2 Example 2:Input: [9,6,4,2,3,5,7,0,1] Output: 8 Note: Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity? My soultion:class Solution: def missingNumber(self, nums): """ :type n.. 더보기
Min Stack Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.push(x) -- Push element x onto stack.pop() -- Removes the element on top of the stack.top() -- Get the top element.getMin() -- Retrieve the minimum element in the stack.Example: MinStack minStack = new MinStack(); minStack.push(-2); minStack.push(0); minStack.push(-3); minStack.getMin(); --> Returns .. 더보기
Valid Parentheses Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.An input string is valid if:Open brackets must be closed by the same type of brackets.Open brackets must be closed in the correct order.Note that an empty string is also considered valid.Example 1:Input: "()" Output: true Example 2:Input: "()[]{}" Output: true Example 3:Input: "(.. 더보기
Pascal's Triangle Given a non-negative integer numRows, generate the first numRows of Pascal's triangle. In Pascal's triangle, each number is the sum of the two numbers directly above it.Example:Input: 5 Output: [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ] My solution:class Solution: def generate(self, numRows): """ :type numRows: int :rtype: List[List[int]] """ result = list() if numRows > 0: result.append([1.. 더보기
Roman to Integer Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000For example, two is written as II in Roman numeral, just two one's added together. Twelve is written as, XII, which is simply X + II. The number twenty seven is written as XXVII, which is XX + V + II.Roman numerals are usually written largest to smallest from left to.. 더보기
Power of Three Given an integer, write a function to determine if it is a power of three.Example 1:Input: 27 Output: true Example 2:Input: 0 Output: falseExample 3:Input: 9 Output: trueExample 4:Input: 45 Output: falseFollow up: Could you do it without using any loop / recursion? My solution:class Solution: def isPowerOfThree(self, n): """ :type n: int :rtype: bool """ if n == 0: return False while n % 3 == 0:.. 더보기
Fizz Buzz Write a program that outputs the string representation of numbers from 1 to n.But for multiples of three it should output “Fizz” instead of the number and for the multiples of five output “Buzz”. For numbers which are multiples of both three and five output “FizzBuzz”.Example:n = 15, Return: [ "1", "2", "Fizz", "4", "Buzz", "Fizz", "7", "8", "Fizz", "Buzz", "11", "Fizz", "13", "14", "FizzBuzz" ].. 더보기
Valid Sudoku Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:Each row must contain the digits 1-9 without repetition.Each column must contain the digits 1-9 without repetition.Each of the 9 3x3 sub-boxes of the grid must contain the digits 1-9 without repetition. A partially filled sudoku which is valid.The Sudoku board could be partially .. 더보기
Rotate Image You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Note:You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.Example 1:Given input matrix = [ [1,2,3], [4,5,6], [7,8,9] ], rotate the input matrix in-place such that it becomes: [ [7,4,1], [8,5,2], [9,6.. 더보기

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