哈夫曼树建立

#include<bits/stdc++.h>
#define NUM 127
#define SOURCE_ADDRESS  "C:\\Users\\XXX\\Desktop\\Input-HuffmanCode-Solitude.txt"
#define DESTINATION_ADDRESS "C:\\Users\\XXX\\Desktop\\Output-HuffmanCode-Solitude.bin"
using namespace std;

char table[NUM][1000] = {0};

struct HuffmanNode{
    char name;
	int fre;
	HuffmanNode * left;
	HuffmanNode * right;
}; 

char * Input(char * address){
	FILE * f = fopen(address, "r"); 
	if(!f){
		perror("error opening file");
		return NULL;
	}
	//确定文件大小 
	fseek(f, 0, SEEK_END);
	long fsize = ftell(f);
	fseek(f, 0, SEEK_SET);
	
	//遍历储存
	char * input = (char *)malloc(fsize + 1);
	if(!input){
		perror("memory error");
		fclose(f);
		return NULL;
	}
	
	//读取信息 
	fread(input, 1, fsize, f);
	input[fsize] = 0;
	
	fclose(f);
	return input;
}

int cmp(const void * a, const void * b){
	return (*(HuffmanNode **)b)->fre - (*(HuffmanNode **)a)->fre;
}

void makeTable(HuffmanNode * root, char pre[1000]){
	
	if(root->left == NULL && root->right == NULL){
		//叶节点时，即编码字符 
		strcpy(table[root->name], pre);
	}
	else{
		//哈夫曼树节点度为2或0，不可能为1 
		char left[1000]; strcpy(left, pre); strcat(left, "1");
		makeTable(root->left, left);
		
		char right[1000]; strcpy(right, pre); strcat(right, "0");
		makeTable(root->right, right);
	}
} 

HuffmanNode * creatNode(char name, int fre = 0, HuffmanNode * l = NULL, HuffmanNode * r = NULL){
	//创建节点 
	HuffmanNode * tem = (HuffmanNode *)malloc(sizeof(HuffmanNode));
	tem->name = name;
	tem->fre = fre;
	tem->left = l;
	tem->right = r;
	return tem;
}

void OutPut(char * adress, char input[], int n){
	//输出到目标文件 
	FILE * f = fopen(adress, "wb");	//open 
	if(!f){
		perror("error opening output file");
		return;
	}
	
	for(int i = 0; i < n; i++){		//output
		fprintf(f, "%s", table[input[i]]);
	}
	
	fclose(f);						//close
} 

int main(){
	//文件读取
	char address[100] = SOURCE_ADDRESS;
	char * input;
	int inputLength;
	input = Input(address);
	inputLength = strlen(input);
	
	//频数统计
	int frequency[NUM] = {0};
	for(int i = 0; i < inputLength; i++){
		if(input[i] == '\n')	continue;
		frequency[input[i]]++;
	} 
	
	//树初始化
	HuffmanNode * trees[NUM];
	for(int i = 0; i < NUM; i++){
		HuffmanNode * t = (HuffmanNode *)malloc(sizeof(HuffmanNode));
		t->name = i;
		t->fre = frequency[i];
		t->left = t->right = NULL;
		trees[i] = t;
	}
	
	//排序
	qsort(trees, NUM, sizeof(HuffmanNode *), cmp);
	
	//构建哈夫曼树
	int size = NUM;
	while(size > 1){
		HuffmanNode * t1 = trees[size-1];
		HuffmanNode * t2 = trees[size-2];
		HuffmanNode * tem = creatNode('-', t1->fre + t2->fre, t1, t2);
		trees[size-2] = tem;
		size--;
		qsort(trees, size, sizeof(HuffmanNode *), cmp);
	}
	
	//编码
	char pre[1000] = "";
	makeTable(trees[0], pre);
	
	//编码输出 
	char address_output[] = DESTINATION_ADDRESS;
	OutPut(address_output, input, inputLength);
	 
	return 0;
}