Data-Structure/Exercise/Homework4/二叉树和等于某值路径.cpp

#include <iostream>
#include <vector>
#include <string>
#include <sstream>
using namespace std;
vector<vector<int>> result; 

template <class T>
struct Node {
    T element;
    Node<T>* left;
    Node<T>* right;
    Node<T>* parent;

    Node(const T& e, Node<T>* p) : element(e), parent(p), left(nullptr), right(nullptr) {}
};

template <class T>
class BinTree {
public:
    Node<T>* root;
    int height;
    vector<T> arr;

    BinTree() : root(nullptr), height(0) {}
    BinTree(const vector<T>& arrs) : arr(arrs), height(0) {}
    void test() {
        for (auto x : arr) {
            cout << x << " ";
        }
    }
    Node<T>* returnroot() {
        return this->root;
    }

    Node<T>* build(int& index, Node<T>* parent) {
        if (index >= arr.size() || arr[index] == 0) {
            index++;
            return nullptr;
        }

        Node<T>* node = new Node<T>(arr[index], parent);
        index++;
        node->left = build(index, node);
        node->right = build(index, node);

        return node;
    }

    void buildTree() {
        int index = 0;
        this->root = build(index, nullptr);
    }

    //输出
    void preorder(Node<T>* node) {
        if (node == nullptr) return;

        cout << node->element << " ";
        preorder(node->left);
        preorder(node->right);
    }
    void inorder(Node<T>* node) {
        if (node == nullptr) return;

        inorder(node->left);
        cout << node->element << " ";
        //cout << ( node->parent == nullptr ? 0 : node->parent->element) << endl;
        inorder(node->right);
    }
    void postorder(Node<T>* node) {
        if (node == nullptr) return;

        postorder(node->left);
        postorder(node->right);
        cout << node->element << " ";
    }
    Node<T>* inorder2(Node<T>* node, const T& x) {
        if (node == nullptr) return nullptr;

        if (node->element == x) {
            return node;
        }

        Node<T>* leftResult = inorder2(node->left, x);
        if (leftResult != nullptr) {
            return leftResult;
        }

        Node<T>* rightResult = inorder2(node->right, x);
        return rightResult;
    }
    void findparent(const T& e) {
        auto x = inorder2(this->root, e);
        if (x == nullptr || x->parent == nullptr) cout << 0 << endl;
        else         cout << x->parent->element << endl;
    }
    void deletesub(Node<T>* node) {
        if (node == nullptr) return;
        deletesub(node->left);
        deletesub(node->right);
        delete node;
    }

    bool deletenode(const T& e) {
        auto x = inorder2(this->root, e);
        if (x == nullptr) return false;
        
        if (x == this->root) {
            deletesub(x);
            this->root = nullptr;
            return true;
        }
        
        if (x->parent->left == x) {
            x->parent->left = nullptr;
        } else {
            x->parent->right = nullptr;
        }
        deletesub(x);
        return true;
    }
    
};

template <class T>
void add(vector<int>& path, Node<T>* n, int sum, int target) {
    if (n == nullptr) return;

    sum += n->element;
    path.push_back(n->element);

    if (n->left == nullptr && n->right == nullptr && sum == target) {
        result.push_back(path);
    }

    add(path, n->left, sum, target);
    add(path, n->right, sum, target);

    path.pop_back();
}



int main() {
    int x = 0;
    vector<int> arr;
    string line;
    getline(cin, line);
    stringstream ss(line);
    int num;

    while (ss >> num) {
        arr.push_back(num);
    }
    BinTree<int> tree(arr);
    tree.buildTree();

    int m;
    cin >> m;//和
    
    vector<int> path;
    add(path, tree.root, 0, m);
    
    if(result.size() == 0) cout << 0 << endl;
    else{
        cout << result.size() << endl;
        for(auto x: result){
            for(auto y: x){
                cout << y << " ";
            }
            cout << endl; 
        }
    }
    
    return 0;
}