feat: add rust codes for space_complexity (#409)

codes/rust/Cargo.toml

@@ -14,6 +14,11 @@ path = "chapter_computational_complexity/time_complexity.rs"
 name = "worst_best_time_complexity"
 path = "chapter_computational_complexity/worst_best_time_complexity.rs"
 
+# Run Command: cargo run --bin space_complexity
+[[bin]]
+name = "space_complexity"
+path = "chapter_computational_complexity/space_complexity.rs"
+
 # Run Command: cargo run --bin leetcode_two_sum
 [[bin]]
 name = "leetcode_two_sum"

codes/rust/chapter_computational_complexity/space_complexity.rs

@@ -0,0 +1,109 @@
+/*
+ * File: space_complexity.rs
+ * Created Time: 2023-03-11
+ * Author: sjinzh (sjinzh@gmail.com)
+ */
+
+include!("../include/include.rs");
+
+use std::collections::HashMap;
+use std::rc::Rc;
+use std::cell::RefCell;
+
+/* 函数 */
+fn function() ->i32 {
+    // do something
+    return 0;
+}
+
+/* 常数阶 */
+#[allow(unused)]
+fn constant(n: i32) {
+    // 常量、变量、对象占用 O(1) 空间
+    const A: i32 = 0;
+    let b = 0;
+    let nums = vec![0; 10000];
+    let node = ListNode::new(0);
+    // 循环中的变量占用 O(1) 空间
+    for i in 0..n {
+        let c = 0;
+    }
+    // 循环中的函数占用 O(1) 空间
+    for i in 0..n {
+        function();
+    }
+}
+
+/* 线性阶 */
+#[allow(unused)]
+fn linear(n: i32) {
+    // 长度为 n 的数组占用 O(n) 空间
+    let mut nums = vec![0; n as usize];
+    // 长度为 n 的列表占用 O(n) 空间
+    let mut nodes = Vec::new();
+    for i in 0..n {
+        nodes.push(ListNode::new(i))
+    }
+    // 长度为 n 的哈希表占用 O(n) 空间
+    let mut map = HashMap::new();
+    for i in 0..n {
+        map.insert(i, i.to_string());
+    }
+}
+
+/* 线性阶（递归实现） */
+fn linear_recur(n: i32) {
+    println!("递归 n = {}", n);
+    if n == 1 {return};
+    linear_recur(n - 1);
+}
+
+/* 平方阶 */
+#[allow(unused)]
+fn quadratic(n: i32) {
+    // 矩阵占用 O(n^2) 空间
+    let num_matrix = vec![vec![0; n as usize]; n as usize];
+    // 二维列表占用 O(n^2) 空间
+    let mut num_list = Vec::new();
+    for i in 0..n {
+        let mut tmp = Vec::new();
+        for j in 0..n {
+            tmp.push(0);
+        }
+        num_list.push(tmp);
+    }
+}
+
+/* 平方阶（递归实现） */
+fn quadratic_recur(n: i32) -> i32 {
+    if n <= 0 {return 0};
+    // 数组 nums 长度为 n, n-1, ..., 2, 1
+    let nums = vec![0; n as usize];
+    println!("递归 n = {} 中的 nums 长度 = {}", n, nums.len());
+    return quadratic_recur(n - 1);
+}
+
+/* 指数阶（建立满二叉树） */
+fn build_tree(n: i32) -> Option<Rc<RefCell<TreeNode>>> {
+    if n == 0 {return None};
+    let root = TreeNode::new(0);
+    root.borrow_mut().left = build_tree(n - 1);
+    root.borrow_mut().right = build_tree(n - 1);
+    return Some(root);
+}
+
+/* Driver Code */
+fn main() {
+    let n = 5;
+    // 常数阶
+    constant(n);
+    // 线性阶
+    linear(n);
+    linear_recur(n);
+    // 平方阶
+    quadratic(n);
+    quadratic_recur(n);
+    // 指数阶
+    let root = build_tree(n);
+    print_util::print_tree(&root.unwrap());   
+}

codes/rust/include/include.rs

@@ -5,6 +5,7 @@
  */
 
 pub mod print_util;
-pub mod tree_node;
 pub mod list_node;
 pub use list_node::ListNode;
+pub mod tree_node;
+pub use tree_node::TreeNode;