Coding Interviews
You are given an integer array prices where prices[i] is the price of a given stock on the ith day.
On each day, you may decide to buy and/or sell the stock. You can only hold at most one share of the stock at any time. However, you can buy it then immediately sell it on the same day.
Find and return the maximum profit you can achieve.
Given a string s, remove duplicate letters so that every letter appears once and only once. You must make sure your result is the smallest in lexicographical order among all possible results.
Given an integer array nums and an integer k, split nums into k non-empty subarrays such that the largest sum of any subarray is minimized.
Return the minimized largest sum of the split.
A subarray is a contiguous part of the array.
You are given an integer n which is the length of a 0-indexed array nums, and a 0-indexed 2D-array ranges, which is a list of sub-ranges of nums (sub-ranges may overlap).
Each row ranges[i] has exactly 2 cells:
ranges[i][0], which shows the start of the ith range (inclusive)
ranges[i][1], which shows the end of the ith range (inclusive)
These ranges cover some cells of nums and leave some cells uncovered. Your task is to find all of the uncovered ranges with maximal length.
Return a 2D-array answer of the uncovered ranges, sorted by the starting point in ascending order.
By all of the uncovered ranges with maximal length, we mean satisfying two conditions:
Each uncovered cell should belong to exactly one sub-range
There should not exist two ranges (l1, r1) and (l2, r2) such that r1 + 1 = l2
Given a positive integer n, return a string representing the smallest positive integer such that the product of its digits is equal to n, or "-1" if no such number exists.
Given a string s, partition s such that every substring of the partition is a palindrome.
Return the minimum cuts needed for a palindrome partitioning of s.
Given an integer array nums, return the length of the longest strictly increasing subsequence.
Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.
You are given n balloons, indexed from 0 to n - 1. Each balloon is painted with a number on it represented by an array nums. You are asked to burst all the balloons.
If you burst the ith balloon, you will get nums[i - 1] * nums[i] * nums[i + 1] coins. If i - 1 or i + 1 goes out of bounds of the array, then treat it as if there is a balloon with a 1 painted on it.
Return the maximum coins you can collect by bursting the balloons wisely.
The demons had captured the princess and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of m x n rooms laid out in a 2D grid. Our valiant knight was initially positioned in the top-left room and must fight his way through dungeon to rescue the princess.
The knight has an initial health point represented by a positive integer. If at any point his health point drops to 0 or below, he dies immediately.
Some of the rooms are guarded by demons (represented by negative integers), so the knight loses health upon entering these rooms; other rooms are either empty (represented as 0) or contain magic orbs that increase the knight's health (represented by positive integers).
To reach the princess as quickly as possible, the knight decides to move only rightward or downward in each step.
Return the knight's minimum initial health so that he can rescue the princess.
Note that any room can contain threats or power-ups, even the first room the knight enters and the bottom-right room where the princess is imprisoned.
A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequence at most once. Note that the path does not need to pass through the root.
The path sum of a path is the sum of the node's values in the path.
Given the root of a binary tree, return the maximum path sum of any non-empty path.
You are given an integer array cost where cost[i] is the cost of ith step on a staircase. Once you pay the cost, you can either climb one or two steps.
You can either start from the step with index 0, or the step with index 1.
Return the minimum cost to reach the top of the floor.
Given an input string s and a pattern p, implement regular expression matching with support for '.' and '*' where:
'.' Matches any single character.
'*' Matches zero or more of the preceding element.
The matching should cover the entire input string (not partial).
Given a rows x cols binary matrix filled with 0's and 1's, find the largest rectangle containing only 1's and return its area.
You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money.
Return the fewest number of coins that you need to make up that amount. If that amount of money cannot be made up by any combination of the coins, return -1.
You may assume that you have an infinite number of each kind of coin.
There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only move either down or right at any point in time.
Given the two integers m and n, return the number of possible unique paths that the robot can take to reach the bottom-right corner.
The thief has found himself a new place for his thievery again. There is only one entrance to this area, called root.
Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that all houses in this place form a binary tree. It will automatically contact the police if two directly-linked houses were broken into on the same night.
Given the root of the binary tree, return the maximum amount of money the thief can rob without alerting the police.
Given a string s, return the longest palindromicsubstringin s.
Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '*' where:
'?' Matches any single character.
'*' Matches any sequence of characters (including the empty sequence).
The matching should cover the entire input string (not partial).
Given an integer n, return the number of structurally unique BST's (binary search trees) which has exactly n nodes of unique values from 1 to n.