Problems
August 16, 2022
N-th tribonacci number
This problem is just like fibonacci number, we will first solve it recursively and then memoize it to reduce redundant calculation.
Time Complexity: O(n)
Space Complexity:...
August 16, 2022
String to integer atoi
First we will strip any whitespace characters, and then check if the length is zero, we immediately return 0. Then we check the sign, if the sign is + or -, we keep that in...
August 15, 2022
Prime number of set bits in binary representation
We will create 2 helper function, one for checking the prime number, another for counting the number of 1 bits. Then we iterate over the range, then count the number of bits, and then check whether...
ReadAugust 15, 2022
Roman to integer
We can replace characters like IV or IX to IIII and VIIII. In that way, when we calculate our result, we can just translate the value to integer...
August 14, 2022
Next greater element I
We traverse nums2 and start storing elements on the top of stack. If current number is greater than the top of the stack, then we found a pair. Keep popping from stack till the top of stack is...
ReadAugust 14, 2022
Word ladder II
We will first run a BFS to create the graph with adjacency list. Then we will run DFS to find all possible paths of that graph.
Time Complexity: O((n+m)*l), n is the number of words,...
August 13, 2022
Design circular queue
We can implement a circular queue by using an array, the maximum size of the array will be the given input k. Then we will keep 2 pointers, one for head and one for tail, and whenever we enqueue some...
ReadAugust 13, 2022
Distinct subsequences
We will check each character of both string, when we find a match, then we have 2 choice, either we include the current index or we skip it. If we don't have a match, we we will skip the current...
ReadAugust 13, 2022
Edit distance
To compute the minimum distance, we will recursively call our decision tree. If i is 0, then we need to insert j characters, if j = 0, then we need in delete i characters. This will be our base case,...
ReadAugust 13, 2022
Regular expression matching
We will go through our decision tree, and then we have 2 choices, either we take the * or we skip it. Based on this logic, we will create a recursive DFS solution for our problem. Then we memoize it...
Read