我正在编写霍夫曼编码。这是我的程序的开始:
using namespace std;
//Counting methods
int *CountCharOccurence(string text)
{
int *charOccurrence = new int[127];
for(int i = 0; i < text.length(); i++)
{
charOccurrence[text[i]]++;
}
return charOccurrence;
}
void DisplayCharOccurence(int *charOccurrence)
{
for(int i = 0; i < 127; i++)
{
if(charOccurrence[i] > 0)
{
cout << (char)i << ": " << charOccurrence[i] << endl;
}
}
}
//Node struct
struct Node
{
public:
char character;
int occurrence;
Node(char c, int occ) {
character = c;
occurrence = occ;
}
bool operator < (const Node* node)
{
return (occurrence < node->occurrence);
}
};
void CreateHuffmanTree(int *charOccurrence)
{
priority_queue<Node*, vector<Node*> > pq;
for(int i = 0; i < 127; i++)
{
if(charOccurrence[i])
{
Node* node = new Node((char)i, charOccurrence[i]);
pq.push(node);
}
}
//Test
while(!pq.empty())
{
cout << "peek: " << pq.top()->character << pq.top()->occurrence << endl;
pq.pop();
}
}
int main(int argc, char** argv) {
int *occurrenceArray;
occurrenceArray = CountCharOccurence("SUSIE SAYS IT IS EASY");
DisplayCharOccurence(occurrenceArray);
CreateHuffmanTree(occurrenceArray);
return (EXIT_SUCCESS);
}
程序首先输出字符及其出现次数。这看起来不错:
: 4 A2 E:2 我:3 小号:6 电话:1 你:1 是:2
但是必须按优先级顺序显示节点内容的测试循环输出:
偷看:Y2 偷看:U1 窥视:S6 偷看:T1 偷看:I3 偷看:E2 窥视:4 窥视:A2
这不是预期的顺序。为什么?