用優先級隊列實現霍夫曼編碼,採用貪心算法,每次從優先級隊列中選取兩個最小元素進行合併。
注意用優先級隊列時用的是小頂堆,採用仿函數做比較器,不能用函數指針來實現。
代碼如下:
#include<iostream>
#include<queue>
using namespace std;
struct Node
{
char c;
int val;
Node *lChild;
Node *rChild;
Node(char cc,int v):c(cc),val(v){}
friend bool operator < (Node n,Node m)
{
return n.val<m.val;
}
};
struct compare
{
bool operator()(Node *first,Node *second)
{
return first->val>second->val;
}
};
bool comp(int first,int second)//優先級隊列中不能用函數指針,只能用函數對象或者重載<
{
return first>second;
}
Node *buildHuffman(char *A,int *V,int N)
{
priority_queue<Node*,vector<Node *>,compare> q;
for(int i=0;i<N;i++)
{
Node *curr=new Node(A[i],V[i]);
q.push(curr);
}
for(int i=1;i<N;i++)
{
Node *x=q.top();
q.pop();
Node *y=q.top();
q.pop();
Node *curr=new Node(0,x->val+y->val);
curr->lChild=x;
curr->rChild=y;
q.push(curr);
}
Node *root=q.top();
q.pop();
return root;
}
int main()
{
char A[]="abcdef";
int V[]={45,13,12,16,9,5};
Node *root=buildHuffman(A,V,6);
system("pause");
return 0;
}