Huffman樹實現編碼譯碼--數據結構實驗

...累了，一會更新，寫註釋，寫思路，最好能畫畫圖

代碼

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<vector>
#include<algorithm>
#include<map>
#include <string>
using namespace std;

typedef struct {
    int val;
    int weight;
    int parent, lchild, rchild;
}HuffmanNode;
static bool cmp(vector<int> a, vector<int> b) {
    return a[1] > b[1];
}
void calculate(vector<vector<int>>& check) {
    FILE* file;
    file = fopen("a.txt", "r");
    char c;
    while ((c = fgetc(file)) != EOF) {
        if (c >= 'a' && c <= 'z') {
            check[c - 'a'][1]++;
        }
        else if (c >= 'A' && c <= 'Z') {
            check[c - 'A' + 26][1]++;
        }
        else if (c == ' ') {
            check[52][1]++;
        }
        else if (c == ',') {
            check[53][1]++;
        }
        else if (c == '.') {
            check[54][1]++;
        }
    }
    sort(check.begin(), check.end(), cmp);
}//統計出現字母的頻率
void initHuffmanTree(HuffmanNode* HT, int n, int m, vector<vector<int>>& check) {
    int j = 1;
    for (int i = n - 1; i >= 0; i--) {
        HT[j++] = {check[i][0], check[i][1],0,0,0};
    }
    for (; j <= m; j++) {
        HT[j] = { 0,0,0,0,0 };
    }
}//初始化哈夫曼樹
void select(HuffmanNode* HT,int endLoc, int& node1, int& node2) {
    int min1 = INT_MAX - 1, min2 = INT_MAX;
    for (int i = 1; i <= endLoc; i++) {
        if (HT[i].parent == 0) {
            if (HT[i].weight < min1) {
                min1 = HT[i].weight;
                node1 = i;
            }
            else if (HT[i].weight < min2) {
                min2 = HT[i].weight;
                node2 = i;
            }
        }
    }
}//選出兩個最小的節點
void createHuffmanTree(HuffmanNode* HT, int n, int m) {
    int loc;
    int node1, node2;
    for (int i = n + 1; i <= m; i++) {
        select(HT, i - 1, node1, node2);
        HT[i].lchild = node2;
        HT[i].rchild = node1;
        HT[i].weight = HT[node1].weight + HT[node2].weight;
        HT[node1].parent = HT[node2].parent = i;
    }
}//創建哈夫曼樹
void encode(HuffmanNode* HT, int n, map<int, string>& huffmanCode) {
    int par; //父節點
    int son; //子節點位置
    for (int i = 1; i <= n; i++) {
        son = i;
        par = HT[i].parent;
        string code = "";
        while (par != 0) {
            if (HT[par].lchild == son) {
                code.insert(code.begin(), '0');
            }
            if (HT[par].rchild == son) {
                code.insert(code.begin(), '1');
            }
            son = par;
            par = HT[par].parent;
        }//向上找，直到沒有parent
        huffmanCode[HT[i].val] = code;
    }
    

}//生成哈夫曼碼
void encodeTxtToHuffmanCode(map<int, string>& huffmanCode) {
    FILE* readFile = fopen("a.txt", "r");
    FILE* writeFile = fopen("b.txt", "w");
    char c = fgetc(readFile);
    while (c != EOF) {
        int i;
        if (c >= 'a' && c <= 'z') {
            i = c - 'a';
        }
        else if (c >= 'A' && c <= 'Z') {
            i = c - 'A' + 26;
        }
        else if (c == ' ') {
            i = 52;
        }
        else if (c == ',') {
            i = 53;
        }
        else if (c == '.') {
            i = 54;
        }
        for (int j = 0; j < huffmanCode[i].size(); j++) {
            fputc(huffmanCode[i][j], writeFile);
        }
        
        c = fgetc(readFile);
    }
    fclose(readFile);
    fclose(writeFile);
}
void decode(HuffmanNode* HT, int n) {
    FILE* readFile = fopen("b.txt", "r");
    FILE* writeFile = fopen("c.txt", "w");
    char c = fgetc(readFile);
    int i = 2 * n - 1;
    while (c != EOF) {
        if (c == '0') {
            i = HT[i].lchild;
        }
        else if (c == '1') {
            i = HT[i].rchild;
        }
        if (HT[i].lchild == 0 || HT[i].rchild == 0) {
            char c;
            if (HT[i].val >= 0 && HT[i].val <= 25) {
                c = 'a' + HT[i].val;
            }
            else if (HT[i].val >= 26 && HT[i].val <= 51) {
                c = 'A' + HT[i].val - 26;
            }
            else if (HT[i].val == 52) {
                c = ' ';
            }
            else if (HT[i].val == 53) {
                c = ',';
            }
            else if (HT[i].val == 54) {
                c = '.';
            }
            fputc(c, writeFile);
            i = 2 * n - 1;
        }
        c = fgetc(readFile);
    }
    fclose(readFile);
    fclose(writeFile);
}//哈夫曼碼翻譯成文章
int main() {
    vector<vector<int>> check(55,vector<int>(2,0));
    for (int i = 0; i < check.size(); i++) {
        check[i][0] = i;
    }
    calculate(check);
    int n = 0; //葉子個數（出現的字母個數）
    for (int i = 0; i < check.size(); i++) {
        if (check[i][1] != 0) n++;
    }


    int m = 2 * n - 1; //Huffman節點
    HuffmanNode* HT;
    HT = (HuffmanNode*)malloc((m + 1) * sizeof(HuffmanNode)); //第0個節點不用

    initHuffmanTree(HT, n, m, check);

    createHuffmanTree(HT, n, m);

    /*for (int i = 1; i <= m; i++) {
        cout << HT[i].val << " " << HT[i].weight << " " << HT[i].parent << " " << HT[i].lchild << " " << HT[i].rchild << endl;
    }*/
    map<int, string> huffmanCode;
    encode(HT, n, huffmanCode);
    /*for (auto x : huffmanCode) {
        cout << x.first << " " << x.second << endl;
    }*/

    encodeTxtToHuffmanCode(huffmanCode);
    
    decode(HT, n);
}