Question

我有一个任务是在bash shell中创建目录的二叉树，深度是作为脚本的第一个参数给出的。每个目录都必须使用第二个参数+目录所在树的深度命名。

示例：./tree.sh 3名称应创建以下结构：

                        name11
                      /        \
                name21          name22
                /    \          /    \
            name31  name32    name33 name34

我真的不知道如何做到这一点，甚至无法开始。它比我迄今为止在bash中所做的任何事情都难。任何帮助都将非常感激。提前谢谢。

Answer 1

使用递归：

#!/bin/bash

level=$1
current_level=$2; current_level=${current_level:=1}
last_number=$3; last_number=${last_number:=1}
prefix="name"

# test to stop recursion
[[ $level -eq $(($current_level-1)) ]] && exit

# first node
new_number=$(($current_level*10+$last_number*2-1))
mkdir "$prefix$new_number"
(
  cd "$prefix$new_number"
  $0 $level $(($current_level+1)) $(($last_number*2-1)) &
)

# second node, not in level 1
if [[ $current_level -ne 1 ]]; then
  new_number=$(($current_level*10+$last_number*2))
  mkdir "$prefix$new_number"
  cd "$prefix$new_number"
  $0 $level $(($current_level+1)) $(($last_number*2)) &
fi

使用./tree.sh 3

进行测试

Answer 2

尽管其他语言更适合实现链接列表，但我不知道为什么这篇文章得到了反对票。

这位专家分享了一些对搜索有益的东西，请看： https://gist.github.com/iestynpryce/4153007

注意： Bash 中二元排序树的实现。使用 eval 伪造了类对象行为。记住，shell 脚本中的 eval 可能是邪恶的。 BT 和 BST 有区别，你可以谷歌一下。

#!/bin/bash
#
# Binary search tree is of the form:
#               10
#              /  \
#             /    \
#            4      16
#           / \    /  
#          1   7  12
#

# Print the binary search tree by doing a recursive call on each node.
# Call the left node, print the value of the current node, call the right node.
# Cost is O(N), where N is the number of elements in the tree, as we have to
# visit each node once.
print_binary_search_tree() {
    local node="$*";
    # Test is the node id is blank, if so return
    if [ "${node}xxx" == "xxx" ]; then
        return;
    fi
    print_binary_search_tree $(eval ${node}.getLeftChild)
    echo $(${node}.getValue)
    print_binary_search_tree $(eval ${node}.getRightChild)
}

### Utility functions to generate a BST ###

# Define set 'methods'
set_node_left() {
    eval "${1}.getLeftChild()  { echo "$2"; }"
}
set_node_right() {
    eval "${1}.getRightChild() { echo "$2"; }"
}
set_node_value() {
    eval "${1}.getValue()      { echo "$2"; }"
}

# Generate unique id:
gen_uid() {
    # prefix 'id' to the uid generated to guarentee
    # it starts with chars, and hence will work as a
    # bash variable
    echo "id$(uuidgen|tr -d '-')";
}

# Generates a new node 'object'
new_node() {
    local node_id="$1";
    local value="$2";
    local left="$3";
    local right="$4";
    eval "${node_id}set='set'";
    eval "set_node_value $node_id $value";
    eval "set_node_left $node_id $right";
    eval "set_node_right $node_id $right";
}

# Inserts a value into a tree with a root node with identifier '$id'.
# If the node, hence the tree does not exist it creates it.
# If the root node is at the either end of the list you'll reach the
# worst case complexity of O(N), where N is the number of elements in 
# the tree. (Average case will be 0(logN).)
tree_insert() {
    local id="$1"
    local value="$2";
    # If id does not exist, create it
    if [ -z "$(eval "echo \$${id}set")" ]; then
        eval "new_node $id $value";
    # If id exists and the value inserted is less than or equal to 
    # the id's node's value. 
    # - Go down the left branch
    elif [[ $value -le $(${id}.getValue) ]]; then
        # Go down to an existing left node if it exists, otherwise
        # create it.
        if [ "$(eval ${id}.getLeftChild)xxx" != "xxx" ]; then
            tree_insert $(eval ${id}.getLeftChild) $value
        else
            local uid=$(gen_uid);
            tree_insert $uid $value;
            set_node_left $id $uid;
        fi
    # Else go down the right branch as the value inserted is larger
    # than the id node's value.
    else 
        # Go down the right node if it exists, else create it
        if [ "$(eval ${id}.getRightChild)xxx" != "xxx" ]; then
            tree_insert $(eval ${id}.getRightChild) $value
        else
            local uid=$(gen_uid);
            tree_insert $uid $value;
            set_node_right $id $uid;
        fi
    fi
}

# Insert an unsorted list of numbers into a binary search tree
for i in 10 4 16 1 7 12; do
    tree_insert bst $i;
done

# Print the binary search tree out in order
print_binary_search_tree bst

实际上，我认为在BASH中实现aa BST非常容易。

如何：只需创建一个 :) 该死的 .txt :) 文件来维护 BST。

在这里，如果使用简单的 .txt 文件实现，我不会展示如何实现插入/填充或删除/更新 BST 节点的 CRUD 操作，但它可以用于打印值。我会尽快解决并分享解决方案。

这是我的解决方案：只是 FYSA 在 BASH 中，我使用了 .txt 文件方法并尝试从此处的任何根节点打印相同的内容：https://stackoverflow.com/a/67341334/1499296

目录UNIX的二叉树

2 个答案: