Shortest Path algo based on edge weight

Applicable for both directed and undirected graph
Shortest path will not have cycle
Shortest path is combinatorial optimization problem
Dijkastra doesn't apply on negative weight
Dijkastra is based on greedy algo using priority queue
Bellman ford is based on dynamic programming
Bellman ford is applicable on even negative weight

Dijkastra Algo to get shortest path from source to destination

Simple greedy approach doesn't solve the problem
Based on optimal greedy approach
Any prefix of the shortest path from S to D must also be optimal
Build shortest path in increasing order of length
It only optimized as per the weight of the path
It doesn't optimize as per the number of hops

Cheapest flight with at most k stops/Bellman ford algo

https://leetcode.com/problems/cheapest-flights-within-k-stops/ https://leetcode.com/problems/network-delay-time/

No need to calculate all predecsoor at a time
Current hops can be initialize by previous value
Look at each edge one at a time
Dijkastra algo doesn't work for negative weight
Bellman ford algo works even for negative weight (as long as there is not negative weight cycle)
Dijkastra time complexity is O(n*logm)
Bellman ford time complexity is O(m*n)

DAG - Directed Acyclic Graph using DP

Find all paths from S to D
Find shortest path from S to D
Find longest path from S to D Time complexity: O (V+E)

Use DP to solve all these problems