https://leetcode.com/problems/sort-list/
Sort a linked list in O(n log n) time using constant space complexity.
Example 1:
Input: 4->2->1->3 Output: 1->2->3->4
呀，天亮了
Mar 13, 2020 01:48:14 AM
https://leetcode.com/problems/sort-list/
Sort a linked list in O(n log n) time using constant space complexity.
Example 1:
Input: 4->2->1->3 Output: 1->2->3->4
Mar 12, 2020 01:36:09 AM
https://leetcode.com/problems/check-if-it-is-a-straight-line/
You are given an array coordinates
, coordinates[i] = [x, y]
, where [x, y]
represents the coordinate of a point. Check if these points make a straight line in the XY plane.
Input: coordinates = [[1,2],[2,3],[3,4],[4,5],[5,6],[6,7]] Output: true
Input: coordinates = [[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]] Output: false
Mar 11, 2020 07:45:24 AM
https://leetcode.com/problems/max-area-of-island/
Given a non-empty 2D array grid
of 0's and 1's, an island is a group of 1
's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.
Find the maximum area of an island in the given 2D array. (If there is no island, the maximum area is 0.)
Example 1:
[[0,0,1,0,0,0,0,1,0,0,0,0,0], [0,0,0,0,0,0,0,1,1,1,0,0,0], [0,1,1,0,1,0,0,0,0,0,0,0,0], [0,1,0,0,1,1,0,0,1,0,1,0,0], [0,1,0,0,1,1,0,0,1,1,1,0,0], [0,0,0,0,0,0,0,0,0,0,1,0,0], [0,0,0,0,0,0,0,1,1,1,0,0,0], [0,0,0,0,0,0,0,1,1,0,0,0,0]]
Given the above grid, return 6
. Note the answer is not 11, because the island must be connected 4-directionally.
Mar 11, 2020 06:36:33 AM
https://leetcode.com/problems/surrounded-regions
Given a 2D board containing 'X'
and 'O'
(the letter O), capture all regions surrounded by 'X'
.
A region is captured by flipping all 'O'
s into 'X'
s in that surrounded region.
Example:
X X X X X O O X X X O X X O X X
After running your function, the board should be:
X X X X X X X X X X X X X O X X
Mar 10, 2020 07:37:16 AM
https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number/
Given the array nums
, for each nums[i]
find out how many numbers in the array are smaller than it. That is, for each nums[i]
you have to count the number of valid j's
such that j != i
and nums[j] < nums[i]
.
Return the answer in an array.
Example 1:
Input: nums = [8,1,2,2,3] Output: [4,0,1,1,3] Explanation: For nums[0]=8 there exist four smaller numbers than it (1, 2, 2 and 3). For nums[1]=1 does not exist any smaller number than it. For nums[2]=2 there exist one smaller number than it (1). For nums[3]=2 there exist one smaller number than it (1). For nums[4]=3 there exist three smaller numbers than it (1, 2 and 2).
Constraints:
2 <= nums.length <= 500
0 <= nums[i] <= 100
Mar 06, 2020 08:39:52 AM
https://leetcode.com/problems/path-sum/
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
Note: A leaf is a node with no children.
Example:
Given the below binary tree and sum = 22
,
5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1
return true, as there exist a root-to-leaf path 5->4->11->2
which sum is 22.
Mar 06, 2020 06:02:19 AM
https://www.geeksforgeeks.org/check-if-the-given-binary-tree-have-a-subtree-with-equal-no-of-1s-and-0s/
Given a Binary Tree having data at nodes as either 0's or 1's. The task is to find out whether there exists a subtree having an equal number of 1's and 0's.
Mar 06, 2020 05:19:07 AM
https://leetcode.com/problems/same-tree/
Given two binary trees, write a function to check if they are the same or not.
Two binary trees are considered the same if they are structurally identical and the nodes have the same value.
Mar 06, 2020 02:01:09 AM
https://leetcode.com/problems/subtree-of-another-tree/
Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node's descendants. The tree s could also be considered as a subtree of itself.
Example 1:
Given tree s:
3 / \ 4 5 / \ 1 2
Given tree t:
4 / \ 1 2
Return true, because t has the same structure and node values with a subtree of s.
Mar 04, 2020 03:35:57 AM
https://leetcode.com/problems/unique-paths-ii/
A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).
The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).
Now consider if some obstacles are added to the grids. How many unique paths would there be?
An obstacle and empty space is marked as 1
and 0
respectively in the grid.
Note: m and n will be at most 100.
Example 1:
Input: [ [0,0,0], [0,1,0], [0,0,0] ] Output: 2 Explanation: There is one obstacle in the middle of the 3x3 grid above. There are two ways to reach the bottom-right corner: 1. Right -> Right -> Down -> Down 2. Down -> Down -> Right -> Right