算法导论 ch16 贪心算法 霍夫曼编码

1. source codes

 

#include <iostream>#include <queue>using namespace std;class TreeNode {private:char data;int frq;TreeNode *left;TreeNode *right;public:TreeNode(char c = '*', int f = 0, TreeNode *l = NULL, TreeNode *r = NULL) :data(c), frq(f), left(l), right(r) {}TreeNode(TreeNode *a, TreeNode *b) :data('*'), frq(a->frq + b->frq), left(a), right(b) {}friend ostream& operator<<(ostream &os, TreeNode *t);template<class T> friend class cmp;};template<class T> class cmp {public:bool operator()(T a, T b) {return a->frq > b->frq;}};ostream& operator<<(ostream &os, TreeNode *t) {os << "node char is "<< t->data<< ", frequency is "<< t->frq<< endl;//if (t->left) {//os << " left child "<< endl;//os << t->left;//}//if (t->right) {//os << " right child "<< endl;//os << t->right;//}return os;}/* * tr: an array storing the data * n: array length */void huffman(priority_queue<TreeNode*, vector<TreeNode*>, cmp<TreeNode*> > pq) {int n = pq.size();for (int i = 1; i < n; i++) {TreeNode* x = pq.top();cout << "x: " << x << endl;pq.pop();TreeNode* y = pq.top();cout << "y: " << y << endl;pq.pop();TreeNode* z = new TreeNode(x, y);pq.push(z);}TreeNode *z = pq.top();cout << z << endl;}int main() {priority_queue<TreeNode*, vector<TreeNode*>, cmp<TreeNode*> > pq;pq.push(new TreeNode('f', 5));pq.push(new TreeNode('e', 9));pq.push(new TreeNode('c', 12));pq.push(new TreeNode('b', 13));pq.push(new TreeNode('d', 16));pq.push(new TreeNode('a', 45));huffman(pq);}

 

2. test result

 

x: node char is f, frequency is 5y: node char is e, frequency is 9x: node char is c, frequency is 12y: node char is b, frequency is 13x: node char is *, frequency is 14y: node char is d, frequency is 16x: node char is *, frequency is 25y: node char is *, frequency is 30x: node char is a, frequency is 45y: node char is *, frequency is 55node char is *, frequency is 100