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add zig codes for Section Binary Tree, Binary Search Tree and AVL Tree (#293)

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* add zig codes for Section 'Binary Tree'

* add zig codes for Section 'Binary Tree'

* add zig codes for Section 'Binary Tree'

* add zig codes for Section 'Binary Tree'

* add zig codes for Section 'Binary Tree' and 'Binary Search Tree'

* update zig codes for Section 'Binary Tree' and 'Binary Search Tree'

* update zig codes for Section 'Binary Tree', 'Binary Search Tree' and 'AVL Tree'
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sjinzh
2023-01-28 00:47:58 +08:00
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parent 3858048d0f
commit b951eb0cfc
5 changed files with 566 additions and 3 deletions
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190
codes/zig/chapter_tree/binary_search_tree.zig Normal file
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// File: binary_search_tree.zig
// Created Time: 2023-01-15
// Author: sjinzh (sjinzh@gmail.com)
const std = @import("std");
const inc = @import("include");
// 二叉搜索树
pub fn BinarySearchTree(comptime T: type) type {
return struct {
const Self = @This();
root: ?*inc.TreeNode(T) = null,
mem_arena: ?std.heap.ArenaAllocator = null,
mem_allocator: std.mem.Allocator = undefined, // 内存分配器
// 构造函数
pub fn init(self: *Self, allocator: std.mem.Allocator, nums: []T) !void {
if (self.mem_arena == null) {
self.mem_arena = std.heap.ArenaAllocator.init(allocator);
self.mem_allocator = self.mem_arena.?.allocator();
}
std.sort.sort(T, nums, {}, comptime std.sort.asc(T)); // 排序数组
self.root = try self.buildTree(nums, 0, nums.len - 1); // 构建二叉搜索树
}
// 析构函数
pub fn deinit(self: *Self) void {
if (self.mem_arena == null) return;
self.mem_arena.?.deinit();
}
// 构建二叉搜索树
fn buildTree(self: *Self, nums: []T, i: usize, j: usize) !?*inc.TreeNode(T) {
if (i > j) return null;
// 将数组中间结点作为根结点
var mid = (i + j) / 2;
var node = try self.mem_allocator.create(inc.TreeNode(T));
node.init(nums[mid]);
// 递归建立左子树和右子树
if (mid >= 1) node.left = try self.buildTree(nums, i, mid - 1);
node.right = try self.buildTree(nums, mid + 1, j);
return node;
}
// 获取二叉树根结点
fn getRoot(self: *Self) ?*inc.TreeNode(T) {
return self.root;
}
// 查找结点
fn search(self: *Self, num: T) ?*inc.TreeNode(T) {
var cur = self.root;
// 循环查找，越过叶结点后跳出
while (cur != null) {
// 目标结点在 cur 的右子树中
if (cur.?.val < num) {
cur = cur.?.right;
// 目标结点在 cur 的左子树中
} else if (cur.?.val > num) {
cur = cur.?.left;
// 找到目标结点，跳出循环
} else {
break;
}
}
// 返回目标结点
return cur;
}
// 插入结点
fn insert(self: *Self, num: T) !?*inc.TreeNode(T) {
// 若树为空，直接提前返回
if (self.root == null) return null;
var cur = self.root;
var pre: ?*inc.TreeNode(T) = null;
// 循环查找，越过叶结点后跳出
while (cur != null) {
// 找到重复结点，直接返回
if (cur.?.val == num) return null;
pre = cur;
// 插入位置在 cur 的右子树中
if (cur.?.val < num) {
cur = cur.?.right;
// 插入位置在 cur 的左子树中
} else {
cur = cur.?.left;
}
}
// 插入结点 val
var node = try self.mem_allocator.create(inc.TreeNode(T));
node.init(num);
if (pre.?.val < num) {
pre.?.right = node;
} else {
pre.?.left = node;
}
return node;
}
// 删除结点
fn remove(self: *Self, num: T) ?*inc.TreeNode(T) {
// 若树为空，直接提前返回
if (self.root == null) return null;
var cur = self.root;
var pre: ?*inc.TreeNode(T) = null;
// 循环查找，越过叶结点后跳出
while (cur != null) {
// 找到待删除结点，跳出循环
if (cur.?.val == num) break;
pre = cur;
// 待删除结点在 cur 的右子树中
if (cur.?.val < num) {
cur = cur.?.right;
// 待删除结点在 cur 的左子树中
} else {
cur = cur.?.left;
}
}
// 若无待删除结点，则直接返回
if (cur == null) return null;
// 子结点数量 = 0 or 1
if (cur.?.left == null or cur.?.right == null) {
// 当子结点数量 = 0 / 1 时， child = null / 该子结点
var child = if (cur.?.left != null) cur.?.left else cur.?.right;
// 删除结点 cur
if (pre.?.left == cur) {
pre.?.left = child;
} else {
pre.?.right = child;
}
// 子结点数量 = 2
} else {
// 获取中序遍历中 cur 的下一个结点
var nex = self.getInOrderNext(cur.?.right);
var tmp = nex.?.val;
// 递归删除结点 nex
_ = self.remove(nex.?.val);
// 将 nex 的值复制给 cur
cur.?.val = tmp;
}
return cur;
}
// 获取中序遍历中的下一个结点（仅适用于 root 有左子结点的情况）
fn getInOrderNext(self: *Self, node: ?*inc.TreeNode(T)) ?*inc.TreeNode(T) {
_ = self;
var node_tmp = node;
if (node_tmp == null) return null;
// 循环访问左子结点，直到叶结点时为最小结点，跳出
while (node_tmp.?.left != null) {
node_tmp = node_tmp.?.left;
}
return node_tmp;
}
};
}
// Driver Code
pub fn main() !void {
// 初始化二叉树
var nums = [_]i32{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
var bst = BinarySearchTree(i32){};
try bst.init(std.heap.page_allocator, &nums);
defer bst.deinit();
std.debug.print("初始化的二叉树为\n", .{});
try inc.PrintUtil.printTree(bst.getRoot(), null, false);
// 查找结点
var node = bst.search(7);
std.debug.print("\n查找到的结点对象为 {any}，结点值 = {}\n", .{node, node.?.val});
// 插入结点
node = try bst.insert(16);
std.debug.print("\n插入结点 16 后，二叉树为\n", .{});
try inc.PrintUtil.printTree(bst.getRoot(), null, false);
// 删除结点
_ = bst.remove(1);
std.debug.print("\n删除结点 1 后，二叉树为\n", .{});
try inc.PrintUtil.printTree(bst.getRoot(), null, false);
_ = bst.remove(2);
std.debug.print("\n删除结点 2 后，二叉树为\n", .{});
try inc.PrintUtil.printTree(bst.getRoot(), null, false);
_ = bst.remove(4);
std.debug.print("\n删除结点 4 后，二叉树为\n", .{});
try inc.PrintUtil.printTree(bst.getRoot(), null, false);
_ = try std.io.getStdIn().reader().readByte();
}