Add old works for Algorithms and Data Structeres

2025-12-04 20:46:45 +02:00
parent 6794e9ca96
commit 6c03e1714f
33 changed files with 1416 additions and 0 deletions
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+/target
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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "graph"
+version = "0.1.0"
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+[package]
+name = "graph"
+version = "0.1.0"
+edition = "2021"
@@ -0,0 +1,67 @@
+# Graph
+
+Implements a weighted, undirected graph with a minimal CLI to build it. Algorithms like Dijkstra's Shortest Path and Kruskal's Minimum Spanning Tree (MST) are available.
+
+Execution result:
+```
+Exit - 'q' or 'x'
+Print the graph - 'p'
+Calculate dijkstra to each vertex - 'd vertex'
+Remove an edge - 'vertex1 vertex2'
+Add an edge - 'vertex1 vertex2 distance'
+1 2 6
+Added 1 - 2, 6
+2 4 5
+Added 2 - 4, 5
+4 5 22
+Added 4 - 5, 22
+5 7 10
+Added 5 - 7, 10
+7 6 12
+Added 7 - 6, 12
+6 1 15
+Added 6 - 1, 15
+3 2 11
+Added 3 - 2, 11
+3 4 17
+Added 3 - 4, 17
+3 6 25
+Added 3 - 6, 25
+3 7 12
+Added 3 - 7, 12
+3 7
+Removed 3 - 7
+3 7 9
+Added 3 - 7, 9
+p
+1 - 2, 6
+1 - 6, 15
+2 - 3, 11
+2 - 4, 5
+3 - 4, 17
+3 - 6, 25
+3 - 7, 9
+4 - 5, 22
+5 - 7, 10
+6 - 7, 12
+d 1
+{1: None, 2: Some((1, 6)), 3: Some((2, 17)), 4: Some((2, 11)), 5: Some((4, 33)), 6: Some((1, 15)), 7: Some((3, 26))}
+q
+1 - 2, 6
+1 - 6, 15
+2 - 3, 11
+2 - 4, 5
+3 - 4, 17
+3 - 6, 25
+3 - 7, 9
+4 - 5, 22
+5 - 7, 10
+6 - 7, 12
+
+1 - 2, 6
+2 - 3, 11
+2 - 4, 5
+3 - 7, 9
+5 - 7, 10
+6 - 7, 12
+```
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+use std::{
+    collections::{BTreeMap, BTreeSet},
+    io,
+};
+
+#[derive(Default)]
+struct Graph {
+    vertices: BTreeMap<usize, BTreeMap<usize, u32>>,
+}
+
+impl Graph {
+    fn rem_edge(&mut self, v1: usize, v2: usize) {
+        self.vertices.entry(v1).and_modify(|m| {
+            m.remove(&v2);
+        });
+        self.vertices.entry(v2).and_modify(|m| {
+            m.remove(&v1);
+        });
+    }
+
+    fn add_edge(&mut self, v1: usize, v2: usize, distance: u32) {
+        self.vertices.entry(v1).or_default().insert(v2, distance);
+        self.vertices.entry(v2).or_default().insert(v1, distance);
+    }
+
+    pub fn new() -> Self {
+        let mut graph = Self::default();
+        println!(
+            "Exit - 'q' or 'x'
+Print the graph - 'p'
+Calculate dijkstra to each vertex - 'd vertex'
+Remove an edge - 'vertex1 vertex2'
+Add an edge - 'vertex1 vertex2 distance'"
+        );
+
+        loop {
+            let mut input = String::new();
+            io::stdin().read_line(&mut input).unwrap();
+            let args: Vec<&str> = input.split_whitespace().collect();
+
+            match args.len() {
+                0 => continue,
+                1 => match args[0] {
+                    "q" | "x" => break,
+                    "p" => graph.print(),
+                    _ => println!("Can't parse {input}"),
+                },
+                2 => {
+                    if args[0] == "d" {
+                        println!("{:?}", graph.dijkstra(args[1].parse().unwrap()));
+                    } else {
+                        graph.rem_edge(args[0].parse().unwrap(), args[1].parse().unwrap());
+                        println!("Removed {} - {}", args[0], args[1]);
+                    }
+                }
+                3 => {
+                    graph.add_edge(
+                        args[0].parse().unwrap(),
+                        args[1].parse().unwrap(),
+                        args[2].parse().unwrap(),
+                    );
+                    println!("Added {} - {}, {}", args[0], args[1], args[2]);
+                }
+                _ => println!("Can't parse {input}"),
+            }
+        }
+
+        graph
+    }
+
+    pub fn print(&self) {
+        let mut viewed = BTreeSet::new();
+
+        for (v1, vertices) in &self.vertices {
+            for (v2, distance) in vertices {
+                if viewed.contains(&(v1, v2)) || viewed.contains(&(v2, v1)) {
+                    continue;
+                }
+
+                println!("{v1} - {v2}, {distance}");
+                viewed.insert((v1, v2));
+            }
+        }
+    }
+
+    // find a representative for a given element
+    fn find_repr(reprs: &BTreeMap<usize, usize>, element: usize) -> usize {
+        if reprs[&element] == element {
+            return element;
+        }
+
+        Self::find_repr(reprs, reprs[&element])
+    }
+
+    pub fn kruskal(&self) -> Self {
+        let mut kruskal_graph = Self::default();
+
+        let mut edges = BTreeSet::new();
+        let mut reprs = BTreeMap::new();
+
+        for (v1, vertices) in &self.vertices {
+            for (v2, distance) in vertices {
+                if !edges.contains(&(*v2, *v1, *distance)) {
+                    edges.insert((*v1, *v2, *distance));
+                }
+            }
+            reprs.insert(*v1, *v1);
+        }
+
+        let mut edges: Vec<_> = edges.into_iter().collect();
+        edges.sort_by_key(|k| k.2);
+
+        let mut count = 0;
+        for (v1, v2, dist) in edges {
+            if count + 1 >= self.vertices.len() {
+                break;
+            }
+
+            let parent1 = Self::find_repr(&reprs, v1);
+            let parent2 = Self::find_repr(&reprs, v2);
+
+            if parent1 != parent2 {
+                count += 1;
+                kruskal_graph.add_edge(v1, v2, dist);
+                reprs.insert(parent2, parent1);
+            }
+        }
+
+        kruskal_graph
+    }
+
+    pub fn dijkstra(&self, start: usize) -> BTreeMap<usize, Option<(usize, u32)>> {
+        let mut visited = BTreeMap::new(); // map of vertices and predecessor with distance
+        let mut fifo = BTreeMap::new(); // first in first out buffer of vertex and distance
+
+        visited.insert(start, None); // doesn't have a predecessor
+
+        // adding vertices from start
+        for (vertex, distance) in &self.vertices[&start] {
+            visited.insert(*vertex, Some((start, *distance)));
+            fifo.insert(*vertex, *distance);
+        }
+
+        while let Some((vertex, distance)) = fifo.pop_first() {
+            for (next, next_distance) in &self.vertices[&vertex] {
+                let new_distance = distance + next_distance;
+                match visited.get(next) {
+                    // skip if new distance >= current distance for vertex
+                    Some(Some((_, current_distance))) if new_distance >= *current_distance => {}
+                    // vertex is a start
+                    Some(None) => {}
+                    // new distance is shorter or next was not in distances
+                    _ => {
+                        visited.insert(*next, Some((vertex, new_distance)));
+                        fifo.insert(*next, new_distance);
+                    }
+                }
+            }
+        }
+
+        visited
+    }
+}
+
+fn main() {
+    let graph = Graph::new();
+    graph.print();
+    println!();
+    graph.kruskal().print();
+}