如何在c++中的结构指针变量树(对于完整树）中存储值

我是编程和c++方面的新手(我想问题的概念在c中也是一样的)。

我正在阅读一个文件作为唯一的参数，其中包含字母表(我代码中的符号)，如"aabbacceaad"，用于计算频率。我的代码计算频率正确。我确信。问题是在我的代码Node*树指针变量(类型为Node)中。我正在用它来创建树。但是，当我尝试根据从重复符号计算的频率创建树时，这个树指针变量只记住for-loop之外最后执行的频率请注意，我只需要使用指针而不是数组。

我的意思是假设我在输入文件中有这样的符号"aabcdedeebbaa"。它的预期输出是：

0  symbol:a  Freq:4  Left 0  Right 0  Index1
1  symbol:b  Freq:3  Left 0  Right 0  Index2
2  symbol:c  Freq:1  Left 0  Right 0  Index3
3  symbol:d  Freq:2  Left 0  Right 0  Index4
4  symbol:e  Freq:3  Left 0  Right 0  Index-1

但我的代码输出是这样的：

0  symbol:e  Freq:3  Left:0  Right:0  Next:5 //Last "e" is executed,tree variable forgot a,b,c and d. 
1  symbol:e  Freq:3  Left:0  Right:0  Next:5
2  symbol:e  Freq:3  Left:0  Right:0  Next:5
3  symbol:e  Freq:3  Left:0  Right:0  Next:5
4  symbol:e  Freq:3  Left:0  Right:0  Next:-1

我的完整c++代码是：

#include <iostream> 
#include <stdlib.h> 
#include <fstream> 
#include <cassert> 
#include <vector>
using namespace std;
class Huffman {
public: int data_size,
length;
Huffman(char * argv);
~Huffman() {};
vector < char > storesym;
vector < int > storefreq;
struct Node
{
int value;
int freq, next;
short flag;
unsigned char symbol;
struct Node * left, * right;
};
Node * tree;
};
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////       CONSTRUCTOR definition        ////////////////////////////////////////////////////////////////////////////////
Huffman::Huffman(char * argv) 
{
char c;
int count = 0;
int flag[256]; //this flag is to know if the alphabet is already counted or not.If counted that i set it to "1" other wise it is "0".Please see below in my code
int j = 0;
FILE * input_file;
int  *symbolarray;
symbolarray=new int[30];
char i, n;
input_file = fopen(argv, "rb");
c = fgetc(input_file);
//////////////////////////////////////////////////////////////////////////////   From here to down i read the alphabbets from file taken as sole argument ///////////////////////////////////////
while (c != EOF && c != 'n' && c != 'r')
{
symbolarray[count] = c;
count++;
c = fgetc(input_file);
}
fclose(input_file);
for (i = 0; i < count; i++)
flag[i] = {0 };
int fcount1 = 0;
for (i = 0; i < count; i++)
{
if (flag[i] == 0)
{
for (j = i; j < count; j++) 
{
if (symbolarray[i] == symbolarray[j]&& flag[j] == 0) 
{
fcount1++;
flag[j] = 1; //**I am setting flag to 1 those alphabets to 1 so that they will not be counted again on next iteration**
}
}
storesym.push_back(symbolarray[i]);
storefreq.push_back(fcount1);
}
fcount1 = 0;
}
cout << endl;
//////////////////////////////////////////////////////////////////////////  ERROR PRONE PART STARTS NOW  /////////////////////////////////////////////////////
for (i = 0; i < storesym.size(); i++) 
{
tree = new Node;  // the problem is here this tree pointer don't store the values for all alphabets, it just remembers the last executed alphabet after this for loop.
tree -> left = NULL;
tree  ->right = NULL;
tree -> symbol = storesym[i];
tree  -> freq = storefreq[i];
tree -> flag = 0;
tree -> next = i + 1;
cout<<"check1 : "<<tree -> symbol<<endl;
} 
////////////////////////////////////////////////////////////////////  eror PRONE PART ENDS HERE  ///////////////////////////////////////////////////////////////////////////////////
cout << "Here is the data read from file" << endl;
n = storesym.size() - 1;
for (int i = 0; i < storesym.size(); i++)
{
if (n == i)
{
tree  -> next = -1;
cout << i << "  symbol:" << tree  -> symbol << "  Freq:" << tree  ->freq << "  Left:" << tree  -> left << "  Right:" << tree  -> right << "  Next:" << tree  -> next << endl;
break;
} else 
{
cout << i << "  symbol:" << tree  -> symbol << "  Freq:" << tree -> freq << "  Left:" << tree  -> left << "  Right:" << tree  ->right << "  Next:" << tree  -> next << endl;
}
}
}
//////////////////////////////////////////////////////////////////////////////////////////////////////
int main(int argc, char * * argv)
{
int freq[256] = {0};
if (argc < 2) {
cout << "Ohh.. Sorry , you forgot to provide the Input File please" << endl;
return (0);
}
Huffman Object1(argv[1]);
return (0);
}

**请帮我如何记住所有的"a，b，c，d和e"(不仅仅是最后一个"e")？我知道只有指针才能做一些事情。