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examples: make the binary search tree example generic (#11968)

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Ruofan XU 2021-09-25 02:17:26 +08:00 committed by GitHub
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1 changed files with 55 additions and 80 deletions
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135
examples/binary_search_tree.v
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@ -1,42 +1,41 @@
// Binary Search Tree example by @SleepyRoy // Binary Search Tree example by @SleepyRoy
// TODO: make Node.value generic once it's robust enough
struct Empty {} struct Empty {}
struct Node { struct Node<T> {
value f64 value T
left Tree left Tree<T>
right Tree right Tree<T>
} }
type Tree = Empty | Node type Tree<T> = Empty | Node<T>
// return size(number of nodes) of BST // return size(number of nodes) of BST
fn size(tree Tree) int { fn (tree Tree<T>) size<T>() int {
return match tree { return match tree {
Empty { 0 } Empty { 0 }
Node { 1 + size(tree.left) + size(tree.right) } Node<T> { 1 + tree.left.size() + tree.right.size() }
} }
} }
// insert a value to BST // insert a value to BST
fn insert(tree Tree, x f64) Tree { fn (tree Tree<T>) insert<T>(x T) Tree<T> {
return match tree { return match tree {
Empty { Empty {
Node{x, tree, tree} Node<T>{x, tree, tree}
} }
Node { Node<T> {
if x == tree.value { if x == tree.value {
tree tree
} else if x < tree.value { } else if x < tree.value {
Node{ Node<T>{
...tree ...tree
left: insert(tree.left, x) left: tree.left.insert(x)
} }
} else { } else {
Node{ Node<T>{
...tree ...tree
right: insert(tree.right, x) right: tree.right.insert(x)
} }
} }
} }
@ -44,80 +43,80 @@ fn insert(tree Tree, x f64) Tree {
} }
// whether able to find a value in BST // whether able to find a value in BST
fn search(tree Tree, x f64) bool { fn (tree Tree<T>) search<T>(x T) bool {
return match tree { return match tree {
Empty { Empty {
false false
} }
Node { Node<T> {
if x == tree.value { if x == tree.value {
true true
} else if x < tree.value { } else if x < tree.value {
search(tree.left, x) tree.left.search(x)
} else { } else {
search(tree.right, x) tree.right.search(x)
} }
} }
} }
} }
// find the minimal value of a BST // find the minimal value of a BST
fn min(tree Tree) f64 { fn (tree Tree<T>) min<T>() T {
return match tree { return match tree {
Empty { Empty {
1e100 T(1e9)
} }
Node { Node<T> {
if tree.value < min(tree.left) { if tree.value < tree.left.min() {
tree.value tree.value
} else { } else {
min(tree.left) tree.left.min()
} }
} }
} }
} }
// delete a value in BST (if nonexistant do nothing) // delete a value in BST (if nonexistant do nothing)
fn delete(tree Tree, x f64) Tree { fn (tree Tree<T>) delete<T>(x T) Tree<T> {
return match tree { return match tree {
Empty { Empty {
tree tree
} }
Node { Node<T> {
if tree.left is Node && tree.right is Node { if tree.left !is Empty && tree.right !is Empty {
if x < tree.value { if x < tree.value {
Node{ Node<T>{
...tree ...tree
left: delete(tree.left, x) left: tree.left.delete(x)
} }
} else if x > tree.value { } else if x > tree.value {
Node{ Node<T>{
...tree ...tree
right: delete(tree.right, x) right: tree.right.delete(x)
} }
} else { } else {
Node{ Node<T>{
...tree ...tree
value: min(tree.right) value: tree.right.min()
right: delete(tree.right, min(tree.right)) right: tree.right.delete(tree.right.min())
} }
} }
} else if tree.left is Node { } else if tree.left !is Empty {
if x == tree.value { if x == tree.value {
tree.left tree.left
} else { } else {
Node{ Node<T>{
...tree ...tree
left: delete(tree.left, x) left: tree.left.delete(x)
} }
} }
} else { } else {
if x == tree.value { if x == tree.value {
tree.right tree.right
} else { } else {
Node{ Node<T>{
...tree ...tree
right: delete(tree.right, x) right: tree.right.delete(x)
} }
} }
} }
@ -126,46 +125,22 @@ fn delete(tree Tree, x f64) Tree {
} }
fn main() { fn main() {
$if !freestanding { mut tree := Tree<f64>(Empty{})
mut tree := Tree(Empty{}) vals := [0.2, 0.0, 0.5, 0.3, 0.6, 0.8, 0.9, 1.0, 0.1, 0.4, 0.7]
input := [0.3, 0.2, 0.5, 0.0, 0.6, 0.8, 0.9, 1.0, 0.1, 0.4, 0.7] for i in vals {
for i in input { tree = tree.insert(i)
tree = insert(tree, i)
}
println('[1] after insertion tree size is ${size(tree)}') // 11
del := [-0.3, 0.0, 0.3, 0.6, 1.0, 1.5]
for i in del {
tree = delete(tree, i)
}
print('[2] after deletion tree size is ${size(tree)}, ') // 7
print('and these elements were deleted: ') // 0.0 0.3 0.6 1.0
for i in input {
if !search(tree, i) {
print('$i ')
}
}
println('')
} $else {
mut tree := Tree(Empty{})
input := [0.3, 0.2, 0.5, 0.0, 0.6, 0.8, 0.9, 1.0, 0.1, 0.4, 0.7]
for i in input {
tree = insert(tree, i)
}
print('[1] after insertion tree size is ') // 11
println(size(tree))
del := [-0.3, 0.0, 0.3, 0.6, 1.0, 1.5]
for i in del {
tree = delete(tree, i)
}
print('[2] after deletion tree size is ') // 7
print(size(tree))
print(', and these elements were deleted: ') // 0.0 0.3 0.6 1.0
for i in input {
if !search(tree, i) {
print(i)
print(' ')
}
}
println('')
} }
println('[1] after insertion tree size is $tree.size()') // 11
del_vals := [-0.3, 0.0, 0.3, 0.6, 1.0, 1.5]
for i in del_vals {
tree = tree.delete(i)
}
print('[2] after deletion tree size is $tree.size(), ') // 7
print('and these elements were deleted: ') // 0.0 0.3 0.6 1.0
for i in vals {
if !tree.search(i) {
print('$i ')
}
}
println('')
} }