Advanced Graph Algorithm
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Minimum Spanning Tree
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Properites:
# It's a tree which means there's no cycle
# It's based on non-directed graph
How to find a spanning tree?
Core idea is to use greedy algorithm and for each step find the edge with minimum weight.
Two ways to build:
# Kruskal's algorithm:
Sort the edge based on weight, then adding each edge to the tree without forming a
cycle.
# Prim's algorithm
Starting from any vertex, insert the adjacent vertices into PQ, and choose the vertex
with minimum edge weight
Data Structure:
Priority Queue
Union Find
Dijkstra's algorithm
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Single Source Shortest Path
Dijkstra's algorithm initializing dist[s] to 0 and all other distTo[] entries to positive infinity. Then, it repeatedly relaxes and adds to the tree a non-tree vertex with the lowest distTo[] value, continuing until all vertices are on the tree or no non-tree vertex has a finite distTo[] value.
Data Structures:
. Priority Queue
. Edges on the shortest-paths tree: edgeTo[v] is the the last edge on a shortest path from s to v.
. Distance to the source: distTo[v] is the length of the shortest path from s to v.
Edge_weighted DAG
Negative Cycles:
Bellman-Ford algorithm.
Initialize distTo[s] to 0 and all other distTo[] values to infinity. Then, considering the digraph's edges in any order, and relax all edges. Make V such passes::
for (int pass = 0; pass < G.V(); pass++)
for (int v = 0; v < G.V(); v++)
for (DirectedEdge e : G.adj(v))
relax(e);
Arbitrage detection. Consider a market for financial transactions that is based on trading commodities.