On a staircase, the i-th step has some non-negative cost cost[i] assigned (0 indexed).
Once you pay the cost, you can either climb one or two steps. You need to find minimum cost to reach the top of the floor, and you can either start from the step with index 0, or the step with index 1.
Example 1:
1 2 3
Input: cost = [10, 15, 20] Output: 15 Explanation: Cheapest is start on cost[1], pay that cost and go to the top.
Example 2:
1 2 3
Input: cost = [1, 100, 1, 1, 1, 100, 1, 1, 100, 1] Output: 6 Explanation: Cheapest is start on cost[0], and only step on 1s, skipping cost[3].
Note:
cost will have a length in the range [2, 1000].
Every cost[i] will be an integer in the range [0, 999].
Given an array nums of integers, you can perform operations on the array.
In each operation, you pick any nums[i] and delete it to earn nums[i] points. After, you must delete every element equal to nums[i] - 1 or nums[i] + 1.
You start with 0 points. Return the maximum number of points you can earn by applying such operations.
Example 1:
1 2 3 4 5
Input: nums = [3, 4, 2] Output: 6 Explanation: Delete 4 to earn 4 points, consequently 3 is also deleted. Then, delete 2 to earn 2 points. 6 total points are earned.
Example 2:
1 2 3 4 5 6
Input: nums = [2, 2, 3, 3, 3, 4] Output: 9 Explanation: Delete 3 to earn 3 points, deleting both 2's and the 4. Then, delete 3 again to earn 3 points, and 3 again to earn 3 points. 9 total points are earned.
Note:
The length of nums is at most 20000.
Each element nums[i] is an integer in the range [1, 10000].
Find the minimum length word from a given dictionary words, which has all the letters from the string licensePlate. Such a word is said to complete the given string licensePlate
Here, for letters we ignore case. For example, "P" on the licensePlate still matches "p" on the word.
It is guaranteed an answer exists. If there are multiple answers, return the one that occurs first in the array.
The license plate might have the same letter occurring multiple times. For example, given a licensePlate of "PP", the word "pair"does not complete the licensePlate, but the word "supper" does.
Example 1:
1 2 3 4 5
Input: licensePlate = "1s3 PSt", words = ["step", "steps", "stripe", "stepple"] Output: "steps" Explanation: The smallest length word that contains the letters "S", "P", "S", and "T". Note that the answer is not "step", because the letter "s" must occur in the word twice. Also note that we ignored case for the purposes of comparing whether a letter exists in the word.
Example 2:
1 2 3 4
Input: licensePlate = "1s3 456", words = ["looks", "pest", "stew", "show"] Output: "pest" Explanation: There are 3 smallest length words that contains the letters "s". We return the one that occurred first.
Note:
licensePlate will be a string with length in range [1, 7].
licensePlate will contain digits, spaces, or letters (uppercase or lowercase).
words will have a length in the range [10, 1000].
Every words[i] will consist of lowercase letters, and have length in range [1, 15].
You have a lock in front of you with 4 circular wheels. Each wheel has 10 slots: '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'. The wheels can rotate freely and wrap around: for example we can turn '9' to be '0', or '0' to be '9'. Each move consists of turning one wheel one slot.
The lock initially starts at '0000', a string representing the state of the 4 wheels.
You are given a list of deadends dead ends, meaning if the lock displays any of these codes, the wheels of the lock will stop turning and you will be unable to open it.
Given a target representing the value of the wheels that will unlock the lock, return the minimum total number of turns required to open the lock, or -1 if it is impossible.
Example 1:
1 2 3 4 5 6
Input: deadends = ["0201","0101","0102","1212","2002"], target = "0202" Output: 6 Explanation: A sequence of valid moves would be "0000" -> "1000" -> "1100" -> "1200" -> "1201" -> "1202" -> "0202". Note that a sequence like "0000" -> "0001" -> "0002" -> "0102" -> "0202" would be invalid, because the wheels of the lock become stuck after the display becomes the dead end "0102".
Example 2:
1 2 3 4
Input: deadends = ["8888"], target = "0009" Output: 1 Explanation: We can turn the last wheel in reverse to move from "0000" -> "0009".
Example 3:
1 2 3 4
Input: deadends = ["8887","8889","8878","8898","8788","8988","7888","9888"], target = "8888" Output: -1 Explanation: We can't reach the target without getting stuck.
Given a start IP address ip and a number of ips we need to cover n, return a representation of the range as a list (of smallest possible length) of CIDR blocks.
A CIDR block is a string consisting of an IP, followed by a slash, and then the prefix length. For example: “123.45.67.89/20”. That prefix length “20” represents the number of common prefix bits in the specified range.
Input: ip = "255.0.0.7", n = 10 Output: ["255.0.0.7/32","255.0.0.8/29","255.0.0.16/32"] Explanation: The initial ip address, when converted to binary, looks like this (spaces added for clarity): 255.0.0.7 -> 11111111 00000000 00000000 00000111 The address "255.0.0.7/32" specifies all addresses with a common prefix of 32 bits to the given address, ie. just this one address.
The address "255.0.0.8/29" specifies all addresses with a common prefix of 29 bits to the given address: 255.0.0.8 -> 11111111 00000000 00000000 00001000 Addresses with common prefix of 29 bits are: 11111111 00000000 00000000 00001000 11111111 00000000 00000000 00001001 11111111 00000000 00000000 00001010 11111111 00000000 00000000 00001011 11111111 00000000 00000000 00001100 11111111 00000000 00000000 00001101 11111111 00000000 00000000 00001110 11111111 00000000 00000000 00001111
The address "255.0.0.16/32" specifies all addresses with a common prefix of 32 bits to the given address, ie. just 11111111 00000000 00000000 00010000.
In total, the answer specifies the range of 10 ips starting with the address 255.0.0.7 .
There were other representations, such as: ["255.0.0.7/32","255.0.0.8/30", "255.0.0.12/30", "255.0.0.16/32"], but our answer was the shortest possible.
Also note that a representation beginning with say, "255.0.0.7/30" would be incorrect, because it includes addresses like 255.0.0.4 = 11111111 00000000 00000000 00000100 that are outside the specified range.
Note:
ip will be a valid IPv4 address.
Every implied address ip + x (for x < n) will be a valid IPv4 address.
We are given a “tree” in the form of a 2D-array, with distinct values for each node.
In the given 2D-array, each element pair [u, v] represents that v is a child of u in the tree.
We can remove exactly one redundant pair in this “tree” to make the result a tree.
You need to find and output such a pair. If there are multiple answers for this question, output the one appearing last in the 2D-array. There is always at least one answer.
Example 1:
1 2 3 4 5 6
Input: [[1,2], [1,3], [2,3]] Output: [2,3] Explanation: Original tree will be like this: 1 / \ 2 - 3
Example 2:
1 2 3 4 5 6
Input: [[1,2], [1,3], [3,1]] Output: [3,1] Explanation: Original tree will be like this: 1 / \\ 2 3
Note:
The size of the input 2D-array will be between 1 and 1000.
Every integer represented in the 2D-array will be between 1 and 2000.
There is a garden with N slots. In each slot, there is a flower. The N flowers will bloom one by one in N days. In each day, there will be exactly one flower blooming and it will be in the status of blooming since then.
Given an array flowers consists of number from 1 to N. Each number in the array represents the place where the flower will open in that day.
For example, flowers[i] = x means that the unique flower that blooms at day i will be at position x, where i and x will be in the range from 1 to N.
Also given an integer k, you need to output in which day there exists two flowers in the status of blooming, and also the number of flowers between them is k and these flowers are not blooming.
If there isn’t such day, output -1.
Example 1:
1 2 3 4 5
Input: flowers: [1,3,2] k: 1 Output: 2 Explanation: In the second day, the first and the third flower have become blooming.
