From 846a5424deed9185178bb9975ff64c66225ff827 Mon Sep 17 00:00:00 2001
From: Michael Bradley <michaelmbrad@gmail.com>
Date: Fri, 31 Jan 2025 01:02:16 -0500
Subject: [PATCH] Implement IndexedBinaryHeap API

Still missing core sift functions, but passes 3/27 tests now
---
 src/backing/indexed/binary_heap.rs | 90 ++++++++++++++++++++++++++----
 1 file changed, 79 insertions(+), 11 deletions(-)

diff --git a/src/backing/indexed/binary_heap.rs b/src/backing/indexed/binary_heap.rs
index 84415ec..d438dce 100644
--- a/src/backing/indexed/binary_heap.rs
+++ b/src/backing/indexed/binary_heap.rs
@@ -1,49 +1,117 @@
 use std::{collections::HashMap, hash::Hash};
 
-use crate::backing::{containers::Pair, indexed::IndexedBacking};
+use crate::backing::{
+    containers::{Pair, SiftResult},
+    indexed::IndexedBacking,
+};
 
-pub struct IndexedBinaryHeap<D: Hash + Clone + Send + Sync, P: PartialOrd + Clone + Send + Sync> {
+pub struct IndexedBinaryHeap<
+    D: Hash + Eq + Clone + Send + Sync,
+    P: PartialOrd + Clone + Send + Sync,
+> {
     data: Vec<Pair<D, P>>,
     indices: HashMap<D, usize>,
 }
 
-impl<D: Hash + Clone + Send + Sync, P: PartialOrd + Clone + Send + Sync> IndexedBinaryHeap<D, P> {
+impl<D: Hash + Eq + Clone + Send + Sync, P: PartialOrd + Clone + Send + Sync>
+    IndexedBinaryHeap<D, P>
+{
     pub fn new() -> Self {
         Self {
             data: Vec::new(),
             indices: HashMap::new(),
         }
     }
+
+    fn sift_up(&mut self, i: usize) -> SiftResult {
+        todo!()
+    }
+
+    fn sift_down(&mut self, i: usize) -> SiftResult {
+        todo!()
+    }
+
+    fn delete_pair(&mut self, i: usize) -> Option<Pair<D, P>> {
+        if i >= self.data.len() {
+            return None;
+        }
+        let pair = self.data[i].clone();
+        if i < self.data.len() - 1 {
+            self.data[i] = self.data.pop().unwrap();
+            if self.data[i] < pair {
+                self.sift_up(i).unwrap();
+            } else {
+                self.sift_down(i).unwrap();
+            }
+        }
+        self.indices.remove(pair.get_data());
+        Some(pair)
+    }
 }
 
-impl<D: Hash + Clone + Send + Sync, P: PartialOrd + Clone + Send + Sync> FromIterator<(D, P)>
+impl<D: Hash + Eq + Clone + Send + Sync, P: PartialOrd + Clone + Send + Sync> FromIterator<(D, P)>
     for IndexedBinaryHeap<D, P>
 {
     fn from_iter<T: IntoIterator<Item = (D, P)>>(iter: T) -> Self {
-        todo!()
+        let mut this = Self::new();
+        for (i, (data, priority)) in iter.into_iter().enumerate() {
+            this.indices.insert(data.clone(), i);
+            this.data.push(Pair::new(data, priority));
+        }
+        for i in (0..=(this.data.len() / 2)).rev() {
+            this.sift_down(i).expect("Index error during heapify");
+        }
+        this
     }
 }
 
-impl<D: Hash + Clone + Send + Sync, P: PartialOrd + Clone + Send + Sync> IndexedBacking<D, P>
+impl<D: Hash + Eq + Clone + Send + Sync, P: PartialOrd + Clone + Send + Sync> IndexedBacking<D, P>
     for IndexedBinaryHeap<D, P>
 {
     fn len(&self) -> usize {
-        todo!()
+        self.data.len()
     }
 
     fn contains(&self, data: &D) -> bool {
-        todo!()
+        self.indices.contains_key(data)
     }
 
     fn set(&mut self, data: D, priority: P) {
-        todo!()
+        if let Some(index) = self.indices.get(&data) {
+            let pair = self.data.get_mut(*index).unwrap();
+            let old_priority = pair.get_priority();
+            if priority < *old_priority {
+                pair.set_priority(priority);
+                self.sift_up(*index).unwrap();
+            } else {
+                pair.set_priority(priority);
+                self.sift_down(*index).unwrap();
+            }
+        } else {
+            let final_index = self.data.len();
+            self.indices.insert(data.clone(), final_index);
+            self.data.push(Pair::new(data, priority));
+            self.sift_up(final_index).unwrap();
+        }
     }
 
     fn remove(&mut self, data: D) -> Option<P> {
-        todo!()
+        if let Some(index) = self.indices.get(&data) {
+            if let Some(pair) = self.delete_pair(*index) {
+                Some(pair.get_priority().clone())
+            } else {
+                None
+            }
+        } else {
+            None
+        }
     }
 
     fn pop(&mut self) -> Option<D> {
-        todo!()
+        if let Some(pair) = self.delete_pair(0) {
+            Some(pair.data())
+        } else {
+            None
+        }
     }
 }