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71 lines
2.2 KiB
71 lines
2.2 KiB
// File: binary_tree_dfs.zig
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// Created Time: 2023-01-15
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// Author: sjinzh (sjinzh@gmail.com)
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const std = @import("std");
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const inc = @import("include");
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var list = std.ArrayList(i32).init(std.heap.page_allocator);
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// 前序遍历
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fn preOrder(comptime T: type, root: ?*inc.TreeNode(T)) !void {
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if (root == null) return;
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// 访问优先级：根结点 -> 左子树 -> 右子树
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try list.append(root.?.val);
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try preOrder(T, root.?.left);
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try preOrder(T, root.?.right);
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}
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// 中序遍历
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fn inOrder(comptime T: type, root: ?*inc.TreeNode(T)) !void {
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if (root == null) return;
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// 访问优先级：左子树 -> 根结点 -> 右子树
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try inOrder(T, root.?.left);
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try list.append(root.?.val);
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try inOrder(T, root.?.right);
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}
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// 后序遍历
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fn postOrder(comptime T: type, root: ?*inc.TreeNode(T)) !void {
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if (root == null) return;
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// 访问优先级：左子树 -> 右子树 -> 根结点
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try postOrder(T, root.?.left);
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try postOrder(T, root.?.right);
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try list.append(root.?.val);
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}
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// Driver Code
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pub fn main() !void {
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// 初始化内存分配器
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var mem_arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
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defer mem_arena.deinit();
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const mem_allocator = mem_arena.allocator();
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// 初始化二叉树
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// 这里借助了一个从数组直接生成二叉树的函数
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var nums = [_]i32{1, 2, 3, 4, 5, 6, 7};
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var root = try inc.TreeUtil.arrToTree(i32, mem_allocator, &nums);
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std.debug.print("初始化二叉树\n", .{});
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try inc.PrintUtil.printTree(root, null, false);
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// 前序遍历
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list.clearRetainingCapacity();
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try preOrder(i32, root);
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std.debug.print("\n前序遍历的结点打印序列 = ", .{});
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inc.PrintUtil.printList(i32, list);
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// 中序遍历
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list.clearRetainingCapacity();
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try inOrder(i32, root);
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std.debug.print("\n中序遍历的结点打印序列 = ", .{});
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inc.PrintUtil.printList(i32, list);
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// 后序遍历
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list.clearRetainingCapacity();
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try postOrder(i32, root);
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std.debug.print("\n后续遍历的结点打印序列 = ", .{});
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inc.PrintUtil.printList(i32, list);
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_ = try std.io.getStdIn().reader().readByte();
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}
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