Start to implement heap

src/heap.rs

@@ -0,0 +1,54 @@
+#[derive(Debug)]
+struct MinHeap<T> {
+    nodes: Vec<T>,
+    size: usize,
+}
+
+fn parent_index(i: usize) -> usize {
+	(i + 1) / 2 - 1
+}
+
+fn child_index(i: usize) -> (usize, usize) {
+	((i + 1) * 2 - 1, (i + 1) * 2 + 1 - 1)
+}
+
+impl<T: std::cmp::PartialOrd> MinHeap<T> {
+    fn new() -> Self {
+        Self {
+            nodes: Vec::with_capacity(128),
+            size: 0,
+        }
+    }
+
+    fn insert(&mut self, e: T) -> () {
+        // append at the end
+        self.nodes.push(e);
+        self.size += 1;
+        let last_index = self.size - 1;
+        let mut swap_index = self.size - 1;
+
+        while swap_index != 0 && self.nodes[last_index] < self.nodes[parent_index(swap_index)] {
+            swap_index = parent_index(swap_index);
+        }
+        self.nodes.swap(last_index, swap_index);
+    }
+
+    fn extract_min(&mut self) -> T {
+    	if self.size == 0 {
+    		panic!("Cannot extract key from empty heap");
+    	}
+    	self.nodes.swap(0, self.size - 1);
+    	let child_indices = child_index(0);
+    	println!("{:?}", child_indices);
+    	self.nodes.pop().unwrap()
+    }
+}
+
+pub fn heap(v: &Vec<u32>) -> () {
+    let mut mh: MinHeap<u32> = MinHeap::new();
+    for i in 0..5 {
+        mh.insert(v[i]);
+        println!("{:?}", mh);
+    }
+    mh.extract_min();
+}

src/main.rs

@@ -1,4 +1,5 @@
 mod dijkstra;
+mod heap;
 mod merge_sort;
 mod min_cut;
 mod quick_sort;
@@ -8,6 +9,7 @@ mod util;
 use std::cmp::min;
 
 use crate::dijkstra::dijkstra;
+use crate::heap::heap;
 use crate::merge_sort::merge_sort_inversions;
 use crate::min_cut::min_cut;
 use crate::quick_sort::quick_sort;
@@ -66,10 +68,17 @@ fn c2a2() {
     // [2599, 2610, 2947, 2052, 2367, 2399, 2029, 2442, 2505, 3068]
 }
 
+#[allow(dead_code)]
+fn c2a3() {
+    let vec = util::read_to_vector("data/c2a3.txt").unwrap();
+    heap(&vec);
+}
+
 fn main() {
     // c1a2();
     // c1a3();
     // c1a4();
     // c2a1();
-    c2a2();
+    // c2a2();
+    c2a3();
 }

src/util.rs

@@ -23,7 +23,7 @@ pub struct DirectedWeightedGraph {
     pub distance: Vec<usize>,
 }
 
-pub fn read_to_vector(path: &str) -> Result<Vec<i64>, io::Error> {
+pub fn read_to_vector(path: &str) -> Result<Vec<u32>, io::Error> {
     let file = File::open(path)?;
     let br = BufReader::new(file);
     let mut v = Vec::new();