Finish course 3 week 1

src/heap.rs

@@ -13,14 +13,15 @@ fn child_indices(index: usize) -> (usize, usize) {
 
 impl<T: std::cmp::PartialOrd> MinHeap<T> {
     fn new() -> Self {
-        Self { nodes: Vec::with_capacity(128) }
+        Self {
+            nodes: Vec::with_capacity(128),
+        }
     }
 
     fn smaller_than_parent(&self, index: usize) -> bool {
         if index == 0 {
             false
         } else {
-
             self.nodes[index] < self.nodes[parent_index(index)]
         }
     }

src/main.rs

@@ -1,25 +1,24 @@
 mod dijkstra;
 mod heap;
+mod jobs;
 mod merge_sort;
 mod min_cut;
+mod prims;
 mod quick_sort;
 mod ssc;
-mod util;
 mod two_sum;
-mod jobs;
-mod prims;
+mod util;
 
-use std::cmp::min;
 use crate::dijkstra::dijkstra;
 use crate::heap::heap;
+use crate::jobs::{jobs_1, jobs_2};
 use crate::merge_sort::merge_sort_inversions;
 use crate::min_cut::min_cut;
+use crate::prims::prims;
 use crate::quick_sort::quick_sort;
 use crate::ssc::ssc;
 use crate::two_sum::find_two_sums;
-use crate::jobs::{jobs_1, jobs_2};
-use crate::prims::prims;
-
+use std::cmp::min;
 
 #[allow(dead_code)]
 fn c1a2() {
@@ -91,15 +90,20 @@ fn c2a4() {
 
 #[allow(dead_code)]
 fn c3a1() {
+    // belongs to c3a1
     let mut jobs = util::read_jobs("data/c3a1_jobs.txt").unwrap();
     let r1 = jobs_1(&mut jobs);
     let r2 = jobs_2(&mut jobs);
-
     let g = util::read_weighted_graph("data/c3a1_edges.txt").unwrap();
     let r3 = prims(&g);
-
     println!("r1 = {}; r2 = {}; r3 = {} ", r1, r2, r3);
-	// r1 = 69119377652; r2 != 67311454237;
+
+    // r1 = 69119377652; r2 = 67311454237; r3 = -3612829
+}
+
+#[allow(dead_code)]
+fn c3a2() {
+    println!("let's go");
 }
 
 fn main() {
@@ -110,5 +114,6 @@ fn main() {
     // c2a2();
     // c2a3();
     // c2a4();
-    c3a1();
+    // c3a1();
+    c3a2();
 }

src/prims.rs

@@ -1,14 +1,49 @@
-#[derive(Debug, Clone)]
+use std::collections::HashSet;
 
+#[derive(Debug, Clone, Copy)]
 pub struct Edge {
-	pub node_a: u32,
-	pub node_b: u32,
-	pub weight: u32,
+    pub weight: i32,
+    pub source_id: usize,
+    pub target_id: usize,
 }
 
-pub type WeightedGraph = Vec<Edge>;
-
-pub fn prims(graph: &WeightedGraph) -> usize {
-	println!("{:?}", graph);
-	42
+#[derive(Debug, Clone)]
+pub struct Vertex {
+    pub id: usize,
+    pub edges: Vec<Edge>,
+}
+
+pub type WeightedGraph = Vec<Vertex>;
+
+pub fn prims(graph: &WeightedGraph) -> i32 {
+    let mut x: HashSet<usize> = HashSet::new();
+    let mut t = Vec::new();
+
+    x.insert(0);
+
+    while x.len() != graph.len() {
+        let mut min_edge = Edge {
+            weight: i32::MAX,
+            source_id: 0,
+            target_id: 0,
+        };
+
+        for node_id in &x {
+            for edge in &graph[*node_id].edges {
+                if edge.weight < min_edge.weight && !x.contains(&edge.target_id) {
+                    min_edge = *edge;
+                }
+            }
+        }
+
+        x.insert(min_edge.target_id);
+        t.push(min_edge);
+    }
+
+    let mut result = 0;
+    for edge in &t {
+        result += edge.weight;
+    }
+
+    result
 }

src/two_sum.rs

@@ -1,6 +1,11 @@
 use std::collections::HashSet;
 
-fn binary_search<T: std::cmp::PartialOrd>(min_i: usize, max_i: usize, xs: &Vec<T>, needle: T) -> usize {
+fn binary_search<T: std::cmp::PartialOrd>(
+    min_i: usize,
+    max_i: usize,
+    xs: &Vec<T>,
+    needle: T,
+) -> usize {
     if min_i >= max_i {
         return max_i;
     }

src/util.rs

@@ -1,9 +1,9 @@
+use crate::jobs::{Job, Jobs};
+use crate::prims::{Edge, Vertex, WeightedGraph};
 use std::fs::File;
 use std::io;
 use std::io::{BufRead, BufReader, Error, ErrorKind};
 use std::vec::Vec;
-use crate::jobs::{Job, Jobs};
-use crate::prims::{WeightedGraph, Edge};
 
 #[derive(Debug, Clone)]
 pub struct Graph {
@@ -163,28 +163,44 @@ pub fn read_jobs(path: &str) -> Result<Jobs, io::Error> {
 }
 
 pub fn read_weighted_graph(path: &str) -> Result<WeightedGraph, io::Error> {
-    let g = Vec::new();
+    let mut g = Vec::new();
     let file = File::open(path)?;
     let br = BufReader::new(file);
     let mut lines = br.lines();
     let line = lines.next().unwrap().unwrap();
-    let mut nodes = line.split_whitespace();
-    let n_nodes: usize = nodes.next().unwrap().parse().unwrap();
-    let n_edges: usize = nodes.next().unwrap().parse().unwrap();
+    let mut fields = line.split_whitespace();
+    let n_nodes: usize = fields.next().unwrap().parse().unwrap();
+    // let n_edges: usize = fields.next().unwrap().parse().unwrap();
 
-    println!("{:?} {:?}", n_nodes, n_edges);
-    // lines.next();
-    // for line in lines {
-    //     let line = line?;
-    //     let mut nodes = line.split_whitespace();
-    //     let weight = nodes.next().unwrap().parse().unwrap();
-    //     let length = nodes.next().unwrap().parse().unwrap();
-    //     let job = Job {
-    //         weight: weight,
-    //         length: length,
-    //     };
-    //     jobs.push(job);
-    // }
+    for i in 0..n_nodes {
+        let node = Vertex {
+            id: i,
+            edges: vec![],
+        };
+        g.push(node);
+    }
+
+    for line in lines {
+        let line = line?;
+        let mut nodes = line.split_whitespace();
+        let id_a: usize = nodes.next().unwrap().parse::<usize>().unwrap() - 1;
+        let id_b: usize = nodes.next().unwrap().parse::<usize>().unwrap() - 1;
+        let weight = nodes.next().unwrap().parse().unwrap();
+
+        let edge = Edge {
+            weight: weight,
+            source_id: id_a,
+            target_id: id_b,
+        };
+        g[id_a].edges.push(edge);
+
+        let edge = Edge {
+            weight: weight,
+            source_id: id_b,
+            target_id: id_a,
+        };
+        g[id_b].edges.push(edge);
+    }
 
     Ok(g)
 }