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| #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_CHARACTERS 256
#define MAX_BIT_LENGTH 1000
typedef struct Node {
char data;
int freq;
struct Node* left;
struct Node* right;
} Node;
typedef struct {
Node* root;
} HuffmanTree;
typedef struct {
char code[MAX_BIT_LENGTH];
int length;
} Code;
Node* createNode(char data, int freq) {
Node* newNode = (Node*)malloc(sizeof(Node));
if (newNode == NULL) {
printf("内存分配失败！\n");
exit(EXIT_FAILURE);
}
newNode->data = data;
newNode->freq = freq;
newNode->left = newNode->right = NULL;
return newNode;
}
void printTree(Node* root, int level) {
if (root != NULL) {
printTree(root->right, level + 1);
for (int i = 0; i < level; i++) printf(" ");
printf("%c(%d)\n", root->data, root->freq);
printTree(root->left, level + 1);
}
}
void encodeHelper(Node* root, char* code, int index, Code* codes[]) {
if (root->left) {
code[index] = '0';
encodeHelper(root->left, code, index + 1, codes);
}
if (root->right) {
code[index] = '1';
encodeHelper(root->right, code, index + 1, codes);
}
if (!root->left && !root->right) {
code[index] = '\0';
Code* newCode = (Code*)malloc(sizeof(Code));
strcpy(newCode->code, code);
newCode->length = index;
codes[(int)root->data] = newCode;
}
}
void encode(HuffmanTree* tree, char* input, char* output) {
FILE* inputFile = fopen(input, "r");
FILE* outputFile = fopen(output, "wb");
if (!inputFile || !outputFile) {
printf("文件打开失败！\n");
exit(EXIT_FAILURE);
}
Code* codes[MAX_CHARACTERS] = { NULL };
char code[MAX_BIT_LENGTH];
encodeHelper(tree->root, code, 0, codes);
char c;
while ((c = fgetc(inputFile)) != EOF) {
Code* currentCode = codes[(int)c];
fwrite(currentCode->code, sizeof(char), currentCode->length, outputFile);
}
fclose(inputFile);
fclose(outputFile);
}
void decode(HuffmanTree* tree, char* input, char* output) {
FILE* inputFile = fopen(input, "rb");
FILE* outputFile = fopen(output, "w");
if (!inputFile || !outputFile) {
printf("文件打开失败！\n");
exit(EXIT_FAILURE);
}
Node* currentNode = tree->root;
char bit;
while ((bit = fgetc(inputFile)) != EOF) {
if (bit == '0') {
currentNode = currentNode->left;
}
else if (bit == '1') {
currentNode = currentNode->right;
}
if (!currentNode->left && !currentNode->right) {
fputc(currentNode->data, outputFile);
currentNode = tree->root;
}
}
fclose(inputFile);
fclose(outputFile);
}
void printCodesToFile(HuffmanTree* tree, char* output) {
FILE* outputFile = fopen(output, "w");
if (!outputFile) {
printf("文件打开失败！\n");
exit(EXIT_FAILURE);
}
char code[MAX_BIT_LENGTH] = "";
encodeHelper(tree->root, code, 0, NULL);
fprintf(outputFile, "Huffman Codes:\n");
for (int i = 0; i < MAX_CHARACTERS; i++) {
if (tree->root[i].freq > 0) {
fprintf(outputFile, "%c: %s\n", (char)i, code);
}
}
fclose(outputFile);
}
int main() {
int n;
printf("输入字符集中的字符数： ");
scanf("%d", &n);
char characters[MAX_CHARACTERS];
int frequencies[MAX_CHARACTERS];
printf("输入字符及其频率：\n");
for (int i = 0; i < n; i++) {
scanf(" %c %d", &characters[i], &frequencies[i]);
}
Node* nodes[MAX_CHARACTERS];
for (int i = 0; i < n; i++) {
nodes[i] = createNode(characters[i], frequencies[i]);
}
for (int i = 0; i < n - 1; i++) {
int min1 = INT_MAX, min2 = INT_MAX;
int minIndex1 = -1, minIndex2 = -1;
for (int j = 0; j < n + i; j++) {
if (nodes[j]->freq < min1) {
min2 = min1;
minIndex2 = minIndex1;
min1 = nodes[j]->freq;
minIndex1 = j;
}
else if (nodes[j]->freq < min2) {
min2 = nodes[j]->freq;
minIndex2 = j;
}
}
Node* newNode = createNode('\0', min1 + min2);
newNode->left = nodes[minIndex1];
newNode->right = nodes[minIndex2];
nodes[minIndex1] = newNode;
nodes[minIndex2] = nodes[n + i];
}
HuffmanTree tree = { nodes[0] };
encode(&tree, "ToBeTran", "CodeFile");
decode(&tree, "CodeFile", "TextFile");
printCodesToFile(&tree, "CodePrint");
printTree(tree.root, 0);
return 0;
}
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