day(24): implement min heap

Signed-off-by: Matej Focko <me@mfocko.xyz>

src/data_structures/min_heap.rs

@@ -0,0 +1,28 @@
+use std::cmp::{Ord, Reverse};
+use std::collections::BinaryHeap;
+
+pub struct MinHeap<T> {
+    heap: BinaryHeap<Reverse<T>>,
+}
+
+impl<T: Ord> MinHeap<T> {
+    pub fn new() -> MinHeap<T> {
+        MinHeap {
+            heap: BinaryHeap::new(),
+        }
+    }
+
+    pub fn push(&mut self, item: T) {
+        self.heap.push(Reverse(item))
+    }
+
+    pub fn pop(&mut self) -> Option<T> {
+        self.heap.pop().map(|Reverse(x)| x)
+    }
+}
+
+impl<T: Ord> Default for MinHeap<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}

src/data_structures/mod.rs

@@ -0,0 +1,2 @@
+mod min_heap;
+pub use min_heap::*;

src/lib.rs

@@ -9,3 +9,6 @@ pub use testing::*;
 
 mod vectors;
 pub use vectors::*;
+
+mod data_structures;
+pub use data_structures::*;