【Openjudg】Huffman编码树

自己做了一遍堆

#include
#include

using namespace std;

template
class Heap{
	T* root;
	int current_size, max_size;
public:
	Heap():root(0), current_size(0), max_size(0){};
	int parent(int cur) const{
		return (cur - 1) / 2;
	}
	int left_child(int cur) const{
		return 2 * cur + 1;
	}
	int right_child(int cur) const{
		return 2 * cur + 1;
	}
	void shift_down(int pos){
		int i = pos;
		int j = left_child(pos);
		T temp = root[pos];
		while(j < current_size){
			if (j + 1 < current_size && root[j + 1] < root[j]){
				j ++;
			}
			if (root[j] < temp){
				root[i] = root[j];
				i = j;
				j = 2 * j + 1;
			}
			else{
				break;
			}
		}
		root[i] = temp;
	}
	void shift_up(int pos){
		T temp = root[pos];
		int i = pos;
		while (i > 0 && temp < root[parent(i)]){
			root[i] = root[parent(i)];
			i = parent(i);
		}
		root[i] = temp;
	}
	void build(const T* array, int amount){
		root = new T[amount];
		current_size = max_size = amount;
		memcpy(root, array, sizeof(T) * amount);
		for (int i = current_size / 2 - 1; i >= 0; i --){
			shift_down(i);
		}
	}
	T heapmin(){
		return root[0];
	}
	bool dlt(int pos){
		if (pos < 0 || pos >= current_size){
			return false;
		}
		T t = root[pos];
		root[pos] = root[--current_size];
		shift_up(pos);
		shift_down(pos);
		return true;
	}
	bool insert(const T& t){
		if (current_size == max_size){
			return false;
		}
		root[current_size] = t;
		shift_up(current_size);
		current_size ++;
		return true;
	}
};

struct _node{
	int data;
	_node* left;
	_node* right;
	_node(int d = 0):data(d), left(NULL), right(NULL){};
	bool isLeaf(){
		return (left == NULL && right == NULL);
	}
	bool operator<(_node t){
		if (data < t.data){
			return true;
		}
		return false;
	}
	void merge(_node &leftc, _node &rightc){
		data = leftc.data + rightc.data;
		left = &leftc;
		right = &rightc;
	}
};

void travel_and_sum(_node *root, int &sum, int &depth){
//	cout << "data " << root->data << endl;
	if(root->isLeaf()){
		sum += depth * root->data;
//		cout << sum << endl;
		depth --;
		return;
	}
	if (root->left){
		depth ++;
		travel_and_sum(root->left, sum, depth);
	}
	if (root->right){
		depth ++;
		travel_and_sum(root->right, sum, depth);
	}
	depth --;
}

int main(){
	int amount;
	cin >> amount;

	_node* root;
	_node heap_array[amount] = {};
	for (int i = 0;i < amount; i ++){
		int data;
		cin >> data;
		heap_array[i].data = data;
	}

	Heap<_node> heap_huff;
	heap_huff.build(heap_array, amount);

	_node *parent, *leftchild, *rightchild;
	for (int i = 0; i < amount - 1; i ++){
		leftchild = new _node(heap_huff.heapmin());	heap_huff.dlt(0);
		rightchild = new _node(heap_huff.heapmin());	heap_huff.dlt(0);
		parent = new _node;
		parent->merge(*leftchild, *rightchild);
		heap_huff.insert(*parent);
		root = parent;
	}

// bi tree travel to compute the sum of wl
	int sum = 0;
	int depth = 0;
	travel_and_sum(root, sum, depth);
	cout << sum;

	return 0;
}