Problems
August 7, 2023
Lowest common ancestor of a binary tree IV
We will use a recursive approach to solve this problem. We will traverse the tree in a post-order fashion. We will return the node if it is equal to any of the nodes in the list of nodes. We will...
ReadJuly 24, 2023
Split strings by separator
We will iterate over the words and split them by the separator. We will then append the non-empty words to the result list.
Time Complexity: O(n) where n is the number of...
June 17, 2023
Number of increasing paths in a grid
We will start DFS from the top left corner of the grid and keep track of the number of paths that we have found so far. We will also keep track of the number of paths that we have found so far for...
ReadJune 14, 2023
Missing ranges
We will add 2 numbers to the existing array lower-1 and upper+1 which will be the lower and upper bound of the range to avoid edge cases. Then we will iterate over the array...
June 13, 2023
Check if all characters have equal number of occurrences
We will count all the occurance of the characters in the string and store it in a hashmap. Then we will check if all the values in the hashmap are equal or not.
Time Complexity: O(n)...
June 11, 2023
Summary ranges
We will iterate over the array and find the ranges. Then we will map the ranges to the required format.
Time complexity: O(n)
Space complexity: O(n)
June 9, 2023
Maximum value at a given index in a bounded array
We can use binary search to find the maximum value at a given index in a bounded array. We can use the formula for the sum of an arithmetic series to find the maximum value at a given index. The...
ReadJune 7, 2023
Check if a number is majority element in a sorted array
We can just count the number of times target appears in nums. If it appears more than len(nums)//2 times, then it is the majority element.
Time complexity:...
June 7, 2023
Count negative numbers in a sorted matrix
We will iterate through each row and count the number of negative numbers in each row. We will add the count to the total count.
Time complexity: O(n)
Space complexity:...
June 5, 2023
Can make arithmetic progression from sequence
We will sort the array and then check if the difference between each element is the same.
Time complexity: O(nlog(n))
Space complexity: O(1)