# 2025q1 Homework2 (quiz1+2)
contributed by <[`kk908676`]((https://github.com/kk908676))>.

# 第 1 週測驗題
### 測驗 一 : 程式碼運作原理

題目核心鏈結串列結構

#include <stddef.h>
typedef struct list_item {
    int value;
    struct list_item *next;
} list_item_t;

typedef struct {
    struct list_item *head;
} list_t;

關鍵操作 `list_insert_before` 函式的語意如下：

測試一：

/* Test inserting at the beginning */
    list_reset();
    my_assert(list_size(&l) == 0, "Initial list size is expected to be zero.");
    for (size_t i = 0; i < N; i++)
        list_insert_before(&l, l.head, &items[i]);
    my_assert(list_size(&l) == N, "Final list size should be N");
    size_t k = N - 1;
    list_item_t *cur = l.head;
    while (cur) {
        my_assert(cur->value == k, "Unexpected list item value");
        k--;
        cur = cur->next;
    }

首先會初始化一個解構指標 `head`
接著在 `head` 指向的鏈結串列最前面新增節點，直到 `N-1` 為止

當 `i = 0` 時

digraph G {
    rankdir=LR;
    node [shape=record];

    head [label="head"];
    p [label="{<data> 0 | <next>}"];

    head -> p;

}

當 `i = 1` 時

digraph G {
    rankdir=LR; 
    node [shape=record]; 

    head [label="head"];
    p [label="{<data> 1 | <next>}"];
    p_prime [label="{<data> 0 | <next>}"];


    head -> p;
    p:next -> p_prime;
}

當 `i = 2` 時

digraph G {
    rankdir=LR;
    node [shape=record]; 

    head [label="head"];
    p [label="{<data> 2 | <next>}"];
    p_prime [label="{<data> 1 | <next>}"];
    p_double_prime [label="{<data> 0 | <next>}"];

    head -> p;
    p:next -> p_prime;
    p_prime:next -> p_double_prime;
}

以此類推...

測試二 :

/* Test inserting at the end */
    list_reset();
    my_assert(list_size(&l) == 0, "Initial list size is expected to be zero.");
    for (size_t i = 0; i < N; i++)
        list_insert_before(&l, NULL, &items[i]);
    my_assert(list_size(&l) == N, "Final list size should be N");
    k = 0;
    cur = l.head;
    while (cur) {
        my_assert(cur->value == k, "Unexpected list item value");
        k++;
        cur = cur->next;
    }

首先會初始化一個解構指標 `head`
接著在 `head` 指向的鏈結串列最後面新增節點，直到 `N-1` 為止

當 `i = 0` 時

digraph G {
    rankdir=LR;
    node [shape=record];

    head [label="head"];
    p [label="{<data> 0 | <next>}"];

    head -> p;

}

當 `i = 1` 時

digraph G {
    rankdir=LR; 
    node [shape=record]; 

    head [label="head"];
    p [label="{<data> 0 | <next>}"];
    p_prime [label="{<data> 1 | <next>}"];


    head -> p;
    p:next -> p_prime;
}

當 `i = 2` 時

digraph G {
    rankdir=LR;
    node [shape=record]; 

    head [label="head"];
    p [label="{<data> 0 | <next>}"];
    p_prime [label="{<data> 1 | <next>}"];
    p_double_prime [label="{<data> 2 | <next>}"];

    head -> p;
    p:next -> p_prime;
    p_prime:next -> p_double_prime;
}

以此類推...

### 測驗 二 : 程式碼運作原理