【发布时间】：2018-05-10 19:15:31
【问题描述】：
我必须为树集编写模板。 叶子的大小为 0。 当 create_empty_set() 被调用时，它应该创建一个叶子，当你添加 T 数据时，叶子应该成为一个分支，并且它的值应该放在左边或右边。不允许重复。 我把老师的指示贴在这里：
So, you'll need three classes: a supertype SortedTree and two subtypes named Branch and Leaf.
LinkedList nodes carried little integers with them. For our set, we want to do something better: we wish
the set to be able to contain any kind of values. The way to accomplish this is to make use of templates:
a TreeSet<T> contains values of type T.
Where do the set's elements reside exactly? Each Branch node contains exactly one T, while the leaves contain nothing:
they merely serve as "plugs" to fill the holes in the tree.
We don't want the T-values to be stored arbitrarily: there'd be no point in using a tree.
We want the values to be sorted. As mentioned above, each branch refers to two nodes (its child nodes) and has its own value.
A branch's value must be larger than all values stored in its left children but less than all values stored in its right children.
For example (leaves are not shown):
[BRANCH 8]
| |
+---------------+ +-------------------+
| |
[BRANCH 4] [BRANCH 11]
| | | |
+-----+ +----+ +-----+ +------+
| | | |
[BRANCH 1] [BRANCH 7] [BRANCH 9] [BRANCH 15]
Take the root node, i.e., the branch carrying 8. All values in its left node (1, 4, 7) are less than 8
and the values in the right children (9, 11, 15) are all greater than 8. The same rule is applicable on each branch in the tree.
Note that no duplicates are allowed: a set cannot contain the same value twice.
我真的很困惑，不知道如何继续。 任何朝着正确方向的推动将不胜感激。
[BRANCH] --> [BRANCH] --> [BRANCH] --> [LEAF]
| | |
| | +-----> [LEAF]
| |
| +-----> [BRANCH] --> [LEAF]
| |
| +-----> [LEAF]
|
+------> [BRANCH] --> [LEAF]
|
+-----> [BRANCH] --> [LEAF]
|
+-----> [LEAF]
这是我已经拥有的。
#ifndef TREE_SET_H
#define TREE_SET_H
#include <memory>
template<typename T>
class TreeSet
{
public:
TreeSet();
virtual int size();
std::shared_ptr<TreeSet<T>> add(T data);
private:
int _size;
T value;
std::shared_ptr<TreeSet<T>> left;
std::shared_ptr<TreeSet<T>> right;
};
template<typename T>
class Leaf : public TreeSet<T> {
public:
Leaf();
private:
};
template<typename T>
class Branch : public TreeSet<T> {
public:
Branch();
private:
};
template <typename T>
TreeSet<T>::TreeSet():_size(0) {
}
template<typename T>
Leaf<T>::Leaf() : TreeSet()
{
}
template<typename T>
Branch<T>::Branch() : TreeSet()
{
}
template<typename T>
std::shared_ptr<TreeSet<T>> create_empty_set()
{
//return std::make_shared<TreeSet<T>>();
return std::make_shared<Leaf<T>>();
}
template<typename T>
int TreeSet<T>::size() {
return _size;
}
template<typename T>
std::shared_ptr<TreeSet<T>> TreeSet<T>::add(T data)
{
return std::shared_ptr<TreeSet<T>>();
}`#endif
`
这是添加测试
#include "Catch.h"
#include "tree-set.h"
#include "util.h"
/*
Add a method named "add" to the hierarchy. The method must take
a value to be added to the set and return a new TreeSet that contains the element.
The original tree must remain unchanged.
Also update Branch's size().
*/
TEST_CASE("Adding element to TreeSet<int> yields new TreeSet<int>")
{
const auto t1 = create_empty_set<int>();
std::shared_ptr<TreeSet<int>> t2 = t1->add(5);
}
TEST_CASE("Adding element to TreeSet<bool> yields new TreeSet<bool>")
{
auto t1 = create_empty_set<bool>();
std::shared_ptr<TreeSet<bool>> t2 = t1->add(true);
}
TEST_CASE("Adding single element increments size from 0 to 1")
{
auto t1 = create_empty_set<bool>();
auto t2 = t1->add(true);
CHECK(t2->size() == 1);
}
TEST_CASE("Adding leaves the original TreeSet unchanged")
{
auto t1 = create_empty_set<char>();
auto t2 = t1->add('a');
CHECK(t1->size() == 0);
}
TEST_CASE("Adding multiple elements increases size by 1 at each time")
{
auto t = create_empty_set<int>();
CHECK(t->size() == 0);
t = t->add(0);
CHECK(t->size() == 1);
t = t->add(1);
CHECK(t->size() == 2);
t = t->add(2);
CHECK(t->size() == 3);
t = t->add(3);
CHECK(t->size() == 4);
}
TEST_CASE("Adding an element already in the set does not increment size")
{
auto t = create_empty_set<int>();
CHECK(t->size() == 0);
t = t->add(0);
CHECK(t->size() == 1);
t = t->add(0);
CHECK(t->size() == 1);
t = t->add(78);
CHECK(t->size() == 2);
t = t->add(78);
CHECK(t->size() == 2);
}
这是另一个测试
/*
Add a method size() to your hierarchy. For now, Branch's implementation of this method
can return a dummy value.
*/
TEST_CASE("Size of an empty TreeSet<int> is zero")
{
const auto t = create_empty_set<int>();
CHECK(t->size() == 0);
}
TEST_CASE("Size of an empty TreeSet<bool> is zero")
{
const auto t = create_empty_set<bool>();
CHECK(t->size() == 0);
}
TEST_CASE("Size of an empty TreeSet<char> is zero")
{
const auto t = create_empty_set<char>();
CHECK(t->size() == 0);
}
TEST_CASE("TreeSet is a polymorphic type (i.e., it contains at least one virtual member)")
{
const auto t = create_empty_set<int>();
CHECK(is_leaf(*t));
}
这是给定的 util.h 头文件
#ifndef UTIL_H
#define UTIL_H
struct Foo
{
bool operator <(const Foo& foo) const
{
return false;
}
};
struct Bar
{
int x;
bool operator <(const Bar& bar) const
{
return x < bar.x;
}
};
template<typename T, typename U>
bool has_dynamic_type(const U& x)
{
return dynamic_cast<const T*>(&x) != nullptr;
}
template<typename T>
bool is_leaf(const TreeSet<T>& x)
{
return has_dynamic_type<Leaf<T>>(x);
}
template<typename T>
bool is_branch(const TreeSet<T>& x)
{
return has_dynamic_type<Branch<T>>(x);
}
#endif
提前致谢， 凯尔维恩
【问题讨论】：
标签： c++ templates binary-tree binary-search-tree treeset