diff --git a/codes/zig/build.zig b/codes/zig/build.zig
index b04b3fd1..e72ca4a5 100644
--- a/codes/zig/build.zig
+++ b/codes/zig/build.zig
@@ -1,46 +1,67 @@
+// File: build.zig
+// Created Time: 2023-01-07
+// Author: sjinzh (sjinzh@gmail.com)
+
 const std = @import("std");
 
-// zig version 0.10.0
+// Zig Version: 0.10.0
+// Zig Codes Build Command: zig build
 pub fn build(b: *std.build.Builder) void {
     const target = b.standardTargetOptions(.{});
     const mode = b.standardReleaseOptions();
 
-    // "chapter_computational_complexity/time_complexity.zig"
-    // Run Command: zig build run_time_complexity
-    const exe_time_complexity = b.addExecutable("time_complexity", "chapter_computational_complexity/time_complexity.zig");
-    exe_time_complexity.addPackagePath("include", "include/include.zig");
-    exe_time_complexity.setTarget(target);
-    exe_time_complexity.setBuildMode(mode);
-    exe_time_complexity.install();
-    const run_cmd_time_complexity = exe_time_complexity.run();
-    run_cmd_time_complexity.step.dependOn(b.getInstallStep());
-    if (b.args) |args| run_cmd_time_complexity.addArgs(args);
-    const run_step_time_complexity = b.step("run_time_complexity", "Run time_complexity");
-    run_step_time_complexity.dependOn(&run_cmd_time_complexity.step);
+    // Section: "Time Complexity"
+        // File: "chapter_computational_complexity/time_complexity.zig"
+        // Run Command: zig build run_time_complexity
+        const exe_time_complexity = b.addExecutable("time_complexity", "chapter_computational_complexity/time_complexity.zig");
+        exe_time_complexity.addPackagePath("include", "include/include.zig");
+        exe_time_complexity.setTarget(target);
+        exe_time_complexity.setBuildMode(mode);
+        exe_time_complexity.install();
+        const run_cmd_time_complexity = exe_time_complexity.run();
+        run_cmd_time_complexity.step.dependOn(b.getInstallStep());
+        if (b.args) |args| run_cmd_time_complexity.addArgs(args);
+        const run_step_time_complexity = b.step("run_time_complexity", "Run time_complexity");
+        run_step_time_complexity.dependOn(&run_cmd_time_complexity.step);
 
-    // "chapter_computational_complexity/worst_best_time_complexity.zig"
-    // Run Command: zig build run_worst_best_time_complexity
-    const exe_worst_best_time_complexity = b.addExecutable("worst_best_time_complexity", "chapter_computational_complexity/worst_best_time_complexity.zig");
-    exe_worst_best_time_complexity.addPackagePath("include", "include/include.zig");
-    exe_worst_best_time_complexity.setTarget(target);
-    exe_worst_best_time_complexity.setBuildMode(mode);
-    exe_worst_best_time_complexity.install();
-    const run_cmd_worst_best_time_complexity = exe_worst_best_time_complexity.run();
-    run_cmd_worst_best_time_complexity.step.dependOn(b.getInstallStep());
-    if (b.args) |args| run_cmd_worst_best_time_complexity.addArgs(args);
-    const run_step_worst_best_time_complexity = b.step("run_worst_best_time_complexity", "Run worst_best_time_complexity");
-    run_step_worst_best_time_complexity.dependOn(&run_cmd_worst_best_time_complexity.step);
+        // File: "chapter_computational_complexity/worst_best_time_complexity.zig"
+        // Run Command: zig build run_worst_best_time_complexity
+        const exe_worst_best_time_complexity = b.addExecutable("worst_best_time_complexity", "chapter_computational_complexity/worst_best_time_complexity.zig");
+        exe_worst_best_time_complexity.addPackagePath("include", "include/include.zig");
+        exe_worst_best_time_complexity.setTarget(target);
+        exe_worst_best_time_complexity.setBuildMode(mode);
+        exe_worst_best_time_complexity.install();
+        const run_cmd_worst_best_time_complexity = exe_worst_best_time_complexity.run();
+        run_cmd_worst_best_time_complexity.step.dependOn(b.getInstallStep());
+        if (b.args) |args| run_cmd_worst_best_time_complexity.addArgs(args);
+        const run_step_worst_best_time_complexity = b.step("run_worst_best_time_complexity", "Run worst_best_time_complexity");
+        run_step_worst_best_time_complexity.dependOn(&run_cmd_worst_best_time_complexity.step);
 
-    // "chapter_computational_complexity/leetcode_two_sum.zig"
-    // Run Command: zig build run_leetcode_two_sum
-    const exe_leetcode_two_sum = b.addExecutable("leetcode_two_sum", "chapter_computational_complexity/leetcode_two_sum.zig");
-    exe_leetcode_two_sum.addPackagePath("include", "include/include.zig");
-    exe_leetcode_two_sum.setTarget(target);
-    exe_leetcode_two_sum.setBuildMode(mode);
-    exe_leetcode_two_sum.install();
-    const run_cmd_leetcode_two_sum = exe_leetcode_two_sum.run();
-    run_cmd_leetcode_two_sum.step.dependOn(b.getInstallStep());
-    if (b.args) |args| run_cmd_leetcode_two_sum.addArgs(args);
-    const run_step_leetcode_two_sum = b.step("run_leetcode_two_sum", "Run leetcode_two_sum");
-    run_step_leetcode_two_sum.dependOn(&run_cmd_leetcode_two_sum.step);
+    // Section: "Space Complexity"
+        // File: "chapter_computational_complexity/space_complexity.zig"
+        // Run Command: zig build run_space_complexity
+        const exe_space_complexity = b.addExecutable("space_complexity", "chapter_computational_complexity/space_complexity.zig");
+        exe_space_complexity.addPackagePath("include", "include/include.zig");
+        exe_space_complexity.setTarget(target);
+        exe_space_complexity.setBuildMode(mode);
+        exe_space_complexity.install();
+        const run_cmd_space_complexity = exe_space_complexity.run();
+        run_cmd_space_complexity.step.dependOn(b.getInstallStep());
+        if (b.args) |args| run_cmd_space_complexity.addArgs(args);
+        const run_step_space_complexity = b.step("run_space_complexity", "Run space_complexity");
+        run_step_space_complexity.dependOn(&run_cmd_space_complexity.step);
+
+    // Section: "Space Time Tradeoff"
+        // File: "chapter_computational_complexity/leetcode_two_sum.zig"
+        // Run Command: zig build run_leetcode_two_sum
+        const exe_leetcode_two_sum = b.addExecutable("leetcode_two_sum", "chapter_computational_complexity/leetcode_two_sum.zig");
+        exe_leetcode_two_sum.addPackagePath("include", "include/include.zig");
+        exe_leetcode_two_sum.setTarget(target);
+        exe_leetcode_two_sum.setBuildMode(mode);
+        exe_leetcode_two_sum.install();
+        const run_cmd_leetcode_two_sum = exe_leetcode_two_sum.run();
+        run_cmd_leetcode_two_sum.step.dependOn(b.getInstallStep());
+        if (b.args) |args| run_cmd_leetcode_two_sum.addArgs(args);
+        const run_step_leetcode_two_sum = b.step("run_leetcode_two_sum", "Run leetcode_two_sum");
+        run_step_leetcode_two_sum.dependOn(&run_cmd_leetcode_two_sum.step);
 }
diff --git a/codes/zig/chapter_computational_complexity/space_complexity.zig b/codes/zig/chapter_computational_complexity/space_complexity.zig
new file mode 100644
index 00000000..9798821a
--- /dev/null
+++ b/codes/zig/chapter_computational_complexity/space_complexity.zig
@@ -0,0 +1,125 @@
+// File: space_complexity.zig
+// Created Time: 2023-01-07
+// Author: sjinzh (sjinzh@gmail.com)
+
+const std = @import("std");
+const inc = @import("include");
+
+// 函数
+fn function() i32 {
+    // do something
+    return 0;
+}
+
+// 常数阶
+fn constant(n: i32) void {
+    // 常量、变量、对象占用 O(1) 空间
+    const a: i32 = 0;
+    var b: i32 = 0;
+    var nums = [_]i32{0}**10000;
+    var node = inc.ListNode(i32){.val = 0};
+    var i: i32 = 0;
+    // 循环中的变量占用 O(1) 空间
+    while (i < n) : (i += 1) {
+        var c: i32 = 0;
+        _ = c;
+    }
+    // 循环中的函数占用 O(1) 空间
+    i = 0;
+    while (i < n) : (i += 1) {
+        _ = function();
+    }
+    _ = a;
+    _ = b;
+    _ = nums;
+    _ = node;
+}
+
+// 线性阶
+fn linear(comptime n: i32) !void {
+    // 长度为 n 的数组占用 O(n) 空间
+    var nums = [_]i32{0}**n;
+    // 长度为 n 的列表占用 O(n) 空间
+    var nodes = std.ArrayList(i32).init(std.heap.page_allocator);
+    defer nodes.deinit();
+    var i: i32 = 0;
+    while (i < n) : (i += 1) {
+        try nodes.append(i);
+    }
+    // 长度为 n 的哈希表占用 O(n) 空间
+    var map = std.AutoArrayHashMap(i32, []const u8).init(std.heap.page_allocator);
+    defer map.deinit();
+    var j: i32 = 0;
+    while (j < n) : (j += 1) {
+        const string = try std.fmt.allocPrint(std.heap.page_allocator, "{d}", .{j});
+        defer std.heap.page_allocator.free(string);
+        try map.put(i, string);
+    }
+    _ = nums;
+}
+
+// 线性阶（递归实现）
+fn linearRecur(comptime n: i32) void {
+    std.debug.print("递归 n = {}\n", .{n});
+    if (n == 1) return;
+    linearRecur(n - 1);
+}
+
+// 平方阶
+fn quadratic(n: i32) !void {
+    // 二维列表占用 O(n^2) 空间
+    var nodes = std.ArrayList(std.ArrayList(i32)).init(std.heap.page_allocator);
+    defer nodes.deinit();
+    var i: i32 = 0;
+    while (i < n) : (i += 1) {
+        var tmp = std.ArrayList(i32).init(std.heap.page_allocator);
+        defer tmp.deinit();
+        var j: i32 = 0;
+        while (j < n) : (j += 1) {
+            try tmp.append(0);
+        }
+        try nodes.append(tmp);
+    }
+}
+
+// 平方阶（递归实现）
+fn quadraticRecur(comptime n: i32) i32 {
+    if (n <= 0) return 0;
+    var nums = [_]i32{0}**n;
+    std.debug.print("递归 n = {} 中的 nums 长度 = {}\n", .{n, nums.len});
+    return quadraticRecur(n - 1);
+}
+
+// 指数阶（建立满二叉树）
+fn buildTree(mem_allocator: std.mem.Allocator, n: i32) !?*inc.TreeNode(i32) {
+    if (n == 0) return null;
+    const root = try mem_allocator.create(inc.TreeNode(i32));
+    root.init(0);
+    root.left = try buildTree(mem_allocator, n - 1);
+    root.right = try buildTree(mem_allocator, n - 1);
+    return root;
+}
+
+// Driver Code
+pub fn main() !void {
+    const n: i32 = 5;
+    // 常数阶
+    constant(n);
+    // 线性阶
+    try linear(n);
+    linearRecur(n);
+    // 平方阶
+    try quadratic(n);
+    _ = quadraticRecur(n);
+    // 指数阶
+    var mem_arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer mem_arena.deinit();
+    var root = blk_root: {
+        const mem_allocator = mem_arena.allocator();
+        break :blk_root try buildTree(mem_allocator, n);
+    };
+    try inc.PrintUtil.printTree(root, null, false);
+
+    const getchar = try std.io.getStdIn().reader().readByte();
+    _ = getchar;
+}
\ No newline at end of file
diff --git a/codes/zig/include/ListNode.zig b/codes/zig/include/ListNode.zig
new file mode 100644
index 00000000..8ce01d3e
--- /dev/null
+++ b/codes/zig/include/ListNode.zig
@@ -0,0 +1,20 @@
+// File: ListNode.zig
+// Created Time: 2023-01-07
+// Author: sjinzh (sjinzh@gmail.com)
+
+const std = @import("std");
+
+// Definition for a singly-linked list node
+pub fn ListNode(comptime T: type) type {
+    return struct {
+        const Self = @This();
+        
+        val: T = 0,
+        next: ?*Self = null,
+
+        // Initialize a list node with specific value
+        pub fn init(self: *Self, x: i32) void {
+            self.val = x;
+        }
+    };
+}
\ No newline at end of file
diff --git a/codes/zig/include/PrintUtil.zig b/codes/zig/include/PrintUtil.zig
index 5adac2a6..8a7dca7a 100644
--- a/codes/zig/include/PrintUtil.zig
+++ b/codes/zig/include/PrintUtil.zig
@@ -1,13 +1,72 @@
-// File: TreeNode.zig
+// File: PrintUtil.zig
 // Created Time: 2023-01-07
 // Author: sjinzh (sjinzh@gmail.com)
 
 const std = @import("std");
+const ListNode = @import("ListNode.zig").ListNode;
+const TreeNode = @import("TreeNode.zig").TreeNode;
 
-// Print an Array
+// Print an array
 pub fn printArray(comptime T: type, nums: []T) void {
     std.debug.print("[", .{});
-    for (nums) |num, j| {
-        std.debug.print("{}{s}", .{num, if (j == nums.len-1) "]\n" else ", " });
-     }
+    if (nums.len > 0) {
+        for (nums) |num, j| {
+            std.debug.print("{}{s}", .{num, if (j == nums.len-1) "]\n" else ", " });
+        }
+    } else {
+        std.debug.print("]", .{});
+        std.debug.print("\n", .{});
+    }
 }
+
+// This tree printer is borrowed from TECHIE DELIGHT
+// https://www.techiedelight.com/c-program-print-binary-tree/
+const Trunk = struct {
+    prev: ?*Trunk = null,
+    str: []const u8 = undefined,
+    
+    pub fn init(self: *Trunk, prev: ?*Trunk, str: []const u8) void {
+        self.prev = prev;
+        self.str = str;
+    }
+};
+
+// Helper function to print branches of the binary tree
+pub fn showTrunks(p: ?*Trunk) void {
+    if (p == null) return;
+    showTrunks(p.?.prev);
+    std.debug.print("{s}", .{p.?.str});
+}
+
+// The interface of the tree printer
+// Print a binary tree
+pub fn printTree(root: ?*TreeNode(i32), prev: ?*Trunk, isLeft: bool) !void {
+    if (root == null) {
+        return;
+    }
+
+    var prev_str = "    ";
+    var trunk = Trunk{.prev = prev, .str = prev_str};
+
+    try printTree(root.?.right, &trunk, true);
+   
+    if (prev == null) {
+        trunk.str = "———";
+    } else if (isLeft) {
+        trunk.str = "/———";
+        prev_str = "   |";
+    } else {
+        trunk.str = "\\———";
+        prev.?.str = prev_str;
+    }
+
+    showTrunks(&trunk);
+    std.debug.print(" {}\n", .{root.?.val});
+
+    if (prev) |_| {
+        prev.?.str = prev_str;
+    }
+    trunk.str = "   |";
+
+    try printTree(root.?.left, &trunk, false);
+}
\ No newline at end of file
diff --git a/codes/zig/include/TreeNode.zig b/codes/zig/include/TreeNode.zig
new file mode 100644
index 00000000..9bd51ba3
--- /dev/null
+++ b/codes/zig/include/TreeNode.zig
@@ -0,0 +1,21 @@
+// File: TreeNode.zig
+// Created Time: 2023-01-07
+// Author: sjinzh (sjinzh@gmail.com)
+
+const std = @import("std");
+
+// Definition for a binary tree node
+pub fn TreeNode(comptime T: type) type {
+    return struct {
+        const Self = @This();
+
+        val: T = undefined,
+        left: ?*Self = null,
+        right: ?*Self = null,
+
+        // Initialize a tree node with specific value
+        pub fn init(self: *Self, x: i32) void {
+            self.val = x;
+        }
+    };   
+}
\ No newline at end of file
diff --git a/codes/zig/include/include.zig b/codes/zig/include/include.zig
index b4f34782..20dfca90 100644
--- a/codes/zig/include/include.zig
+++ b/codes/zig/include/include.zig
@@ -1,5 +1,7 @@
 // File: include.zig
-// Created Time: 2023-01-04
+// Created Time: 2023-01-07
 // Author: sjinzh (sjinzh@gmail.com)
 
-pub const PrintUtil = @import("PrintUtil.zig");
\ No newline at end of file
+pub const PrintUtil = @import("PrintUtil.zig");
+pub const ListNode = @import("ListNode.zig").ListNode;
+pub const TreeNode = @import("TreeNode.zig").TreeNode;
\ No newline at end of file