https://leetcode.com/problems/power-of-two/
Given an integer, write a function to determine if it is a power of two.
Example 1:
Input: 1 Output: true Explanation: 20 = 1
Example 2:
Input: 16 Output: true Explanation: 24 = 16
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Jun 09, 2020 12:36:12 AM
https://leetcode.com/problems/power-of-two/
Given an integer, write a function to determine if it is a power of two.
Example 1:
Input: 1 Output: true Explanation: 20 = 1
Example 2:
Input: 16 Output: true Explanation: 24 = 16
Jun 08, 2020 02:12:28 AM
https://leetcode.com/problems/index-pairs-of-a-string/
Given a text
string and words
(a list of strings), return all index pairs [i, j]
so that the substring text[i]...text[j]
is in the list of words
.
Example 1:
Input: text = "thestoryofleetcodeandme", words = ["story","fleet","leetcode"] Output: [[3,7],[9,13],[10,17]]
Jun 08, 2020 01:56:33 AM
https://leetcode.com/problems/coin-change-2/
You are given coins of different denominations and a total amount of money. Write a function to compute the number of combinations that make up that amount. You may assume that you have infinite number of each kind of coin.
Example 1:
Input: amount = 5, coins = [1, 2, 5] Output: 4 Explanation: there are four ways to make up the amount: 5=5 5=2+2+1 5=2+1+1+1 5=1+1+1+1+1
Jun 06, 2020 04:29:25 AM
https://leetcode.com/problems/reverse-linked-list-ii/
Reverse a linked list from position m to n. Do it in one-pass.
Note: 1 ≤ m ≤ n ≤ length of list.
Example:
Input: 1->2->3->4->5->NULL, m = 2, n = 4 Output: 1->4->3->2->5->NULL
Jun 05, 2020 08:40:24 AM
https://leetcode.com/problems/reverse-linked-list/
Reverse a singly linked list.
Example:
Input: 1->2->3->4->5->NULL Output: 5->4->3->2->1->NULL
Follow up:
A linked list can be reversed either iteratively or recursively. Could you implement both?
Jun 05, 2020 07:23:06 AM
https://leetcode.com/problems/remove-zero-sum-consecutive-nodes-from-linked-list/
Given the head
of a linked list, we repeatedly delete consecutive sequences of nodes that sum to 0
until there are no such sequences.
After doing so, return the head of the final linked list. You may return any such answer.
(Note that in the examples below, all sequences are serializations of ListNode
objects.)
Example 1:
Input: head = [1,2,-3,3,1] Output: [3,1] Note: The answer [1,2,1] would also be accepted.
Jun 04, 2020 01:30:38 AM
https://leetcode.com/problems/two-city-scheduling/
There are 2N
people a company is planning to interview. The cost of flying the i
-th person to city A
is costs[i][0]
, and the cost of flying the i
-th person to city B
is costs[i][1]
.
Return the minimum cost to fly every person to a city such that exactly N
people arrive in each city.
Example 1:
Input: [[10,20],[30,200],[400,50],[30,20]] Output: 110 Explanation: The first person goes to city A for a cost of 10. The second person goes to city A for a cost of 30. The third person goes to city B for a cost of 50. The fourth person goes to city B for a cost of 20. The total minimum cost is 10 + 30 + 50 + 20 = 110 to have half the people interviewing in each city.
Jun 03, 2020 07:15:54 AM
https://leetcode.com/problems/compare-version-numbers/
Compare two version numbers version1 and version2.
If version1 > version2
return 1;
if version1 < version2
return -1;
otherwise return 0
.
You may assume that the version strings are non-empty and contain only digits and the .
character.
The .
character does not represent a decimal point and is used to separate number sequences.
For instance, 2.5
is not "two and a half" or "half way to version three", it is the fifth second-level revision of the second first-level revision.
You may assume the default revision number for each level of a version number to be 0
. For example, version number 3.4
has a revision number of 3
and 4
for its first and second level revision number. Its third and fourth level revision number are both 0
.
Example 1:
Input:version1
= "0.1",version2
= "1.1" Output: -1
Jun 02, 2020 06:44:48 AM
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 1000
For 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 right. However, the numeral for four is not IIII
. Instead, the number four is written as IV
. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX
. There are six instances where subtraction is used:
I
can be placed before V
(5) and X
(10) to make 4 and 9. X
can be placed before L
(50) and C
(100) to make 40 and 90. C
can be placed before D
(500) and M
(1000) to make 400 and 900.Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.
Example 1:
Input: 3 Output: "III"
Jun 02, 2020 12:26:30 AM
https://leetcode.com/problems/invert-binary-tree/
Invert a binary tree.
Example:
Input:
4 / \ 2 7 / \ / \ 1 3 6 9
Output:
4 / \ 7 2 / \ / \ 9 6 3 1