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124 lines
3.2 KiB
124 lines
3.2 KiB
// File: space_complexity.zig
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// Created Time: 2023-01-07
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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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// 函数
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fn function() i32 {
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// do something
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return 0;
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}
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// 常数阶
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fn constant(n: i32) void {
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// 常量、变量、对象占用 O(1) 空间
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const a: i32 = 0;
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var b: i32 = 0;
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var nums = [_]i32{0}**10000;
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var node = inc.ListNode(i32){.val = 0};
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var i: i32 = 0;
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// 循环中的变量占用 O(1) 空间
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while (i < n) : (i += 1) {
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var c: i32 = 0;
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_ = c;
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}
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// 循环中的函数占用 O(1) 空间
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i = 0;
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while (i < n) : (i += 1) {
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_ = function();
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}
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_ = a;
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_ = b;
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_ = nums;
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_ = node;
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}
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// 线性阶
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fn linear(comptime n: i32) !void {
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// 长度为 n 的数组占用 O(n) 空间
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var nums = [_]i32{0}**n;
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// 长度为 n 的列表占用 O(n) 空间
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var nodes = std.ArrayList(i32).init(std.heap.page_allocator);
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defer nodes.deinit();
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var i: i32 = 0;
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while (i < n) : (i += 1) {
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try nodes.append(i);
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}
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// 长度为 n 的哈希表占用 O(n) 空间
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var map = std.AutoArrayHashMap(i32, []const u8).init(std.heap.page_allocator);
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defer map.deinit();
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var j: i32 = 0;
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while (j < n) : (j += 1) {
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const string = try std.fmt.allocPrint(std.heap.page_allocator, "{d}", .{j});
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defer std.heap.page_allocator.free(string);
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try map.put(i, string);
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}
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_ = nums;
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}
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// 线性阶（递归实现）
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fn linearRecur(comptime n: i32) void {
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std.debug.print("递归 n = {}\n", .{n});
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if (n == 1) return;
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linearRecur(n - 1);
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}
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// 平方阶
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fn quadratic(n: i32) !void {
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// 二维列表占用 O(n^2) 空间
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var nodes = std.ArrayList(std.ArrayList(i32)).init(std.heap.page_allocator);
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defer nodes.deinit();
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var i: i32 = 0;
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while (i < n) : (i += 1) {
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var tmp = std.ArrayList(i32).init(std.heap.page_allocator);
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defer tmp.deinit();
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var j: i32 = 0;
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while (j < n) : (j += 1) {
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try tmp.append(0);
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}
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try nodes.append(tmp);
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}
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}
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// 平方阶（递归实现）
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fn quadraticRecur(comptime n: i32) i32 {
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if (n <= 0) return 0;
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var nums = [_]i32{0}**n;
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std.debug.print("递归 n = {} 中的 nums 长度 = {}\n", .{n, nums.len});
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return quadraticRecur(n - 1);
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}
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// 指数阶（建立满二叉树）
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fn buildTree(mem_allocator: std.mem.Allocator, n: i32) !?*inc.TreeNode(i32) {
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if (n == 0) return null;
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const root = try mem_allocator.create(inc.TreeNode(i32));
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root.init(0);
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root.left = try buildTree(mem_allocator, n - 1);
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root.right = try buildTree(mem_allocator, n - 1);
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return root;
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}
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// Driver Code
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pub fn main() !void {
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const n: i32 = 5;
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// 常数阶
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constant(n);
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// 线性阶
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try linear(n);
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linearRecur(n);
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// 平方阶
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try quadratic(n);
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_ = quadraticRecur(n);
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// 指数阶
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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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var root = blk_root: {
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const mem_allocator = mem_arena.allocator();
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break :blk_root try buildTree(mem_allocator, n);
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};
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try inc.PrintUtil.printTree(root, null, false);
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_ = try std.io.getStdIn().reader().readByte();
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} |