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#include <stdio.h>
#include <string.h>
#include<fstream>
#include<string>
#include<iostream>
using namespace std;
typedef struct node_t {
struct node_t *left, *right;
int freq;
char c;
} *node;
struct node_t pool[256] = {{0}};
node qqq[255], *q = qqq - 1;
int n_nodes = 0, qend = 1;
char *code[128] = {0}, buf[1024];
node new_node(int freq, char c, node a, node b)
{
node n = pool + n_nodes++;
if (freq) n->c = c, n->freq = freq;
else {
n->left = a, n->right = b;
n->freq = a->freq + b->freq;
}
return n;
}
/* priority queue */
void qinsert(node n)
{
int j, i = qend++;
while ((j = i / 2)) {
if (q[j]->freq <= n->freq) break;
q[i] = q[j], i = j;
}
q[i] = n;
}
node qremove()
{
int i, l;
node n = q[i = 1];
if (qend < 2) return 0;
qend--;
while ((l = i * 2) < qend) {
if (l + 1 < qend && q[l + 1]->freq < q[l]->freq) l++;
q[i] = q[l], i = l;
}
q[i] = q[qend];
return n;
}
/* walk the tree and put 0s and 1s */
void build_code(node n, char *s, int len)
{
static char *out = buf;
if (n->c) {
s[len] = 0;
strcpy(out, s);
code[n->c] = out;
out += len + 1;
return;
}
s[len] = '0'; build_code(n->left, s, len + 1);
s[len] = '1'; build_code(n->right, s, len + 1);
}
void init(const char *s)
{
int i, freq[128] = {0};
char c[16];
while (*s) freq[(int)*s++]++;
for (i = 0; i < 128; i++)
if (freq[i]) qinsert(new_node(freq[i], i, 0, 0));
while (qend > 2)
qinsert(new_node(0, 0, qremove(), qremove()));
build_code(q[1], c, 0);
}
void encode(const char *s, char *out)
{
while (*s) {
strcpy(out, code[*s]);
out += strlen(code[*s++]);
}
}
void decode(const char *s, node t)
{
node n = t;
while (*s) {
if (*s++ == '0') n = n->left;
else n = n->right;
if (n->c) putchar(n->c), n = t;
}
putchar('\n');putchar('\n');
if (t != n) printf("garbage input\n");
}
int main(void)
{
int i;
string filename;
ifstream myfile;
cout<<"Please Enter File Name that you want to Encode: ";
getline(cin,filename);
filename += ".txt";
myfile.open(filename.c_str());
std::string str;
str.assign( (std::istreambuf_iterator<char>(myfile) ),
(std::istreambuf_iterator<char>() ) );
std::cout<<"\n"<<str<<endl<<endl;
const char * c = str.c_str();
char buf[1024];
init(c);
for (i = 0; i < 128; i++)
if (code[i]) printf("'%c': %s\n", i, code[i]);
encode(c, buf);
ofstream binfile("binary.txt");
if(binfile.is_open())
{
binfile<<buf;
binfile.close();
}
printf("\nEncoded:\n%s\n", buf);
printf("\n\nDecoded:\n");
ifstream dfile("binary.txt");
while(getline(dfile,str))
cout<<str<<endl<<endl;
const char * y = str.c_str();
decode(y, q[1]);
return 0;
}
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