hello-algo/codes/zig/chapter_tree/binary_tree_bfs.zig

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// File: binary_tree_bfs.zig
// Created Time: 2023-01-15
// Author: sjinzh (sjinzh@gmail.com)
const std = @import("std");
const inc = @import("include");
// 层序遍历
fn hierOrder(comptime T: type, mem_allocator: std.mem.Allocator, root: *inc.TreeNode(T)) !std.ArrayList(T) {
// 初始化队列,加入根结点
const L = std.TailQueue(*inc.TreeNode(T));
var queue = L{};
var root_node = try mem_allocator.create(L.Node);
root_node.data = root;
queue.append(root_node);
// 初始化一个列表,用于保存遍历序列
var list = std.ArrayList(T).init(std.heap.page_allocator);
while (queue.len > 0) {
var queue_node = queue.popFirst().?; // 队列出队
var node = queue_node.data;
try list.append(node.val); // 保存结点
if (node.left != null) {
var tmp_node = try mem_allocator.create(L.Node);
tmp_node.data = node.left.?;
queue.append(tmp_node); // 左子结点入队
}
if (node.right != null) {
var tmp_node = try mem_allocator.create(L.Node);
tmp_node.data = node.right.?;
queue.append(tmp_node); // 右子结点入队
}
}
return list;
}
// Driver Code
pub fn main() !void {
// 初始化内存分配器
var mem_arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
defer mem_arena.deinit();
const mem_allocator = mem_arena.allocator();
// 初始化二叉树
// 这里借助了一个从数组直接生成二叉树的函数
var nums = [_]i32{1, 2, 3, 4, 5, 6, 7};
var root = try inc.TreeUtil.arrToTree(i32, mem_allocator, &nums);
std.debug.print("初始化二叉树\n", .{});
try inc.PrintUtil.printTree(root, null, false);
// 层序遍历
var list = try hierOrder(i32, mem_allocator, root.?);
defer list.deinit();
std.debug.print("\n层序遍历的结点打印序列 = ", .{});
inc.PrintUtil.printList(i32, list);
_ = try std.io.getStdIn().reader().readByte();
}