The intuition is pretty straight forward which is to use map. But we have to keep two separate maps to record the mapping from s to t and the other from t to s. Then we loop through s and… Read More »Leetcode 205 Isomorphic Strings
The idea is pretty simple, we use a map to record the number appearance for each letter from the ransomNote. Then we go to magazine and see if each letter can be used in the ransomNote. Each time we see… Read More »Leetcode 383 Ransom Note
The most intuitive solution would be to go over each cell of the board, base on its neighbors, record the new value in a temporary board. Then after all cells are done, we loop through the original board again and… Read More »Leetcode 289 Game of Life
There are straight forward solutions for this problem but they are require extra space. The best solution only ask for O(1) of space. The reason why we need extra space in the first place is because we need to store… Read More »Leetcode 73 Set Matrix Zeroes
This is an interesting problem which looks complex but essentially there are just 2 steps we need to do this. Solution Javascript: Time Complexity:O(n^2) since we visited all the cells in the matrix Space Complexity:O(1) since it’s in place
This is indeed a very interesting problem. If we simulate the process, there are a couple of key points to notice: Solution Javascript: Time Complexity:O(m*n) since we visited all the cells in the matrix Space Complexity:O(1)
The first thing comes into mind is sliding window since this is a substring related problem. The idea is pretty simple actually. javascript: Time Complexity:We looped through both t and s once, so the time complexity is O(m + n)… Read More »Leetcode 76 Minimum Window Substring
To address this problem, we can use either Breadth-First Search (BFS) since it’s more suitable for finding the shortest path in an unweighted graph, similar to determining the minimum number of mutations required. The core idea is to represent each… Read More »Leetcode 433 Minimum Genetic Mutation
Problem Statement Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly two or zero sub-node. If the node has two sub-nodes, then this node’s value is the smaller value among its two… Read More »Leetcode 671 Second Minimum Node In a Binary Tree
Problem Statement Given a 1-indexed array of integers numbers that is already sorted in non-decreasing order, find two numbers such that they add up to a specific target number. Let these two numbers be numbers[index1] and numbers[index2] where 1 <= index1 < index2 <= numbers.length. Return the indices of the two numbers, index1 and index2, added by… Read More »Leetcode 167 Two Sum II – Input Array Is Sorted