Problems
May 17, 2023
Number of good leaf nodes pairs
We can traverse the tree and find out the distance between each pair of leaf nodes. If the distance is less than or equal to the given distance, we increment the result by 1. Time complexity:...
ReadMay 17, 2023
Diameter of N-ary tree
We will use recursive DFS to find out the longest path in the tree. The longest path will be the diameter of the tree.
Time complexity: O(n) where n is the number of nodes in the...
May 15, 2023
Remove sub folders from the filesystem
We can use a trie data structure to store all the folders. We will iterate over the folders and insert them into the trie. If we find a folder that is already present in the trie, we will mark it as...
ReadMay 14, 2023
Consecutive characters
We will keep track of the consecutive characters in a variable count. We will iterate over the string and if the current character is same as the previous character, we will increment...
May 13, 2023
Maximum product of two elements in an array
We will use a heap to get the two largest elements in the array. Then we will return the product of the two largest elements each substructed by 1.
Time complexity: O(n)
Space...
May 13, 2023
Count triplets that can form two arrays of equal xor
We will calculate the prefix xor for each index. Then we will iterate over all possible pairs of indices and check if the xor of the prefix xors of the two indices is 0. If it is, we will increment...
ReadMay 13, 2023
Make array zero by subtracting equal amounts
We can solve this problem by using a heap. We will add all the elements to the heap. Then we will pop the largest element from the heap and substruct it from all the other elements. We will repeat...
ReadMay 12, 2023
Find permutation
Loop on the input and insert a decreasing numbers when see a 'I'. Or insert a decreasing numbers to complete the result.
Time complexity: O(n)
Space complexity: O(1)
May 12, 2023
Count ways to build good strings
All we care about is low and high. We subtruct from high number of zeros or number of ones if can. Same we do for low but max it with 0. If we reached 0 in low than we add one to the answer. Time...
ReadMay 12, 2023
Android unlock patterns
We can use backtracking to solve the problem. We will start from the first number and try to find all possible patterns. We will use a hashmap to store the numbers that are already used. Now we will...
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