In this blog post, we'll explore different Domain Specific Languages (DSL) operations that can be applied on BinaryHeap
BinaryHeap
A priority queue implemented with a binary heap. By default, it will be a max-heap (i.e., when we retrieve values from BinaryHeap using pop(), peek() methods, max value will be returned)
In case, if we use core::cmp::Reverse struct to push items to BinaryHeap, then it will be called as min-heap (i.e., when we retrieve values from BinaryHeap using pop(), peek() methods, min value will be returned)
For more details, please check this page from rust documentation.
BinaryHeap (as max-heap) code examples
Creating new BinaryHeap (max-heap) using new constructor method
// Create new BinaryHeap (Max-Heap) let mut bh = BinaryHeap::new(); bh.push(10); bh.push(20); bh.push(30); bh.push(40); bh.push(50); Creating new BinaryHeap (max-heap) using From trait's from method
// Creating BinaryHeap (Max-Heap) using From trait let bh1 = BinaryHeap::from([1, 2, 3, 4, 5]); Creating new BinaryHeap (max-heap) using IntoIterator trait's collect method
// Creating BinaryHeap (Max-Heap) using IntoInterator trait let bh2: BinaryHeap<i32> = vec![1, 2, 3, 4, 5].into_iter().collect(); Iterating BinaryHeap (max-heap) elements
// iterator doesnt guarantee the order of items println!("Iterating over BinaryHeap (max-heap):"); for x in &bh { println!("{x}"); } Retrieving elements using peek and pop methods of BinaryHeap (max-heap)
// Peek method used to get greatest item in the BinaryHeap (Max-Heap) if let Some(t) = bh.peek() { println!("Greatest item from BinaryHeap (max-heap): {}", t); } // pop method returns items from max to min items println!("Loop through BinaryHeap (max-heap) and retrieve element using pop method:"); while let Some(top) = bh.pop() { println!("Retrieving element using pop() method from BinaryHeap (max-heap): {top}"); } BinaryHeap (as min-heap) code examples
Creating new BinaryHeap (min-heap) using new constructor method
// Create new BinaryHeap (Min-Heap) let mut bh3 = BinaryHeap::new(); bh3.push(core::cmp::Reverse(10)); bh3.push(core::cmp::Reverse(20)); bh3.push(core::cmp::Reverse(30)); bh3.push(core::cmp::Reverse(40)); bh3.push(core::cmp::Reverse(50)); Creating new BinaryHeap (min-heap) using From trait's from method
// Creating BinaryHeap (Min-Heap) using From trait let bh4 = BinaryHeap::from([ core::cmp::Reverse(1), core::cmp::Reverse(2), core::cmp::Reverse(3), core::cmp::Reverse(4), core::cmp::Reverse(5), ]); Creating new BinaryHeap (min-heap) using IntoIterator trait's collect method
// Creating BinaryHeap (Min-Heap) using IntoInterator trait let bh5: BinaryHeap<core::cmp::Reverse<i32>> = vec![ core::cmp::Reverse(1), core::cmp::Reverse(2), core::cmp::Reverse(3), core::cmp::Reverse(4), core::cmp::Reverse(5), ] .into_iter() .collect(); Iterating BinaryHeap (min-heap) elements
// iterator doesnt guarantee the order of items for x in &bh5 { println!("Element from BinaryHeap (min-heap) {:?}", x); } Retrieving elements using peek and pop methods of BinaryHeap (min-heap)
// Peek method used to get greatest item in the BinaryHeap (Min-Heap) if let Some(t) = bh3.peek() { println!("Greatest item from BinaryHeap (min-heap): {:?}", t); } // pop method returns items from min to max items while let Some(top) = bh3.pop() { println!( "Retrieving element using pop() method from BinaryHeap (min-heap): {:?}", top ); } DSL operations on BinaryHeap
Some of the useful DSL operations that can be performed on BinaryHeap as below
sum method on BinaryHeap through Iterator trait
// Finding sum of all elements println!( "Sum of all elements from BinaryHeap: {}", bh1.iter().sum::<i32>() ); product method on BinaryHeap through Iterator trait
// Finding product of all elements println!( "Product of all elements from BinaryHeap: {}", bh1.iter().product::<i32>() ); zip method on BinaryHeap through Iterator trait
// Merge 2 different vector and create Tuple object let j = vec![10, 9, 8, 7, 6, 5, 4, 3, 2, 1]; let t = bh1.iter().zip(j.iter()); t.for_each(|x| println!("Zipped Vector with BinaryHeap: {:?} ", x)); Create another type out from BinaryHeap
It is possible to create completely different type out from BinaryHeap using Iterator trait's collect method
Create HashMap type from BinaryHeap
// Following operation will create a HashMap with each VecDeque element as Key and len as Value let mut s: BinaryHeap<&str> = BinaryHeap::new(); s.push("Rust"); s.push("is"); s.push("awesome"); let hm1: HashMap<_, _> = s.iter().map(|x| (x, x.len())).collect(); println!("Created HashMap out from BinaryHeap: {:?}", hm1); All the code examples can be found in this link
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Happy reading!!!
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