# Graph Problem ## Dijkstra Refer to : > http://nthucad.cs.nthu.edu.tw/~yyliu/personal/nou/04ds/dijkstra.html  Find the minimum distance from a start node to any other nodes. **Algorithm:** 1. Construct a hash map that record the minimum distance from a to others in the current step. || a | b| c |d | e | f | g | |---- | -------- | -------- | -------- |-------- |-------- |-------- |-------- | | Step1 | ∞| ∞ | ∞ |∞ |∞ |∞ |∞ |

# Trie ## Trie Node & Dictionary Search Tree Refere to https://leetcode.com/problems/implement-trie-prefix-tree/ Let's consider a problem that we want to search an word from a dictionary. For example, **dictionary = {apple, ball, boat, code, command, coworker, zebra} words = command** *M : the length of the word we want to search N : number of words in the dictionary* * **Brute-Force** Firstly, we come up with an idea that store the dictionary into a hash set. Then, compare each **"comma

# Non-local means Filter ### 1. Bilateral Filter Bilateral filter is an algorithm that consider spatial information and pixel value informaiton in the same time. That is why it is so-called "Bi"-lateral. * In natural image, the variation in spatial domain is low which means there are high correlation between the central pixel and its neighborhoods. * However, this assumption will greatly blur the results in the edge boundary which lost the edge features. Therefore, we compensate the flawness

# Edge Detection using Adaptive Filter --- ### 1. Introduction Edge detection is one of the most common used technique in image analysis. It is also a critical element in image processing since edge contains lots of useful information. An edge can be describe as as a boundary between two regions separated by distinction in strong intensity values of the pixels. Edge detection can be define as a process of finding and tracing sharp discontinuities in the image. It has been widely used in object r