10、广义表

1、广义的定义和初始化

#include<stdio.h>
#include<malloc.h>
#include<string.h>
#include<assert.h>
#include<stdlib.h>

#define ATOM_TYPE int


typedef enum {
    HEAD,
    ATOM,
    CHILDLIST
} ElementType;

typedef struct GLNode {
    ElementType tag;  // 标记位, 用于区分原子结点和表节点
    union {
        ATOM_TYPE atom;  // 原子节点的值域
        struct GLNode *hp;  // 表节点的表头指针
    };
    struct GLNode *tp;  // 指向下一个元素节点
} GLNode;

typedef GLNode* GenList;  // 广义表 类型是一种扩展的线性链表

void InitGenList(GenList* gl){
    *gl = NULL;
}

2、广义表的创建

// 分离表头和表尾元素
int separate(char* sub, char* hsub) {
    if (sub[0] == '\0' || strcmp(sub, "()") == 0) {
        hsub[0] = '\0';
        return 1;
    }
    int n = strlen(sub);
    int i = 0, k = 0;  // 用于判断首字符为 ( 的情况
    while (i < n && (sub[i] != ',' || k != 0)) {
        if (sub[i] == '(') k++;
        else if (sub[i] == ')') k--;
        i++;
    }
    if (i < n) {
        strncpy(hsub, sub, i);
        hsub[i] = '\0';
        strcpy((char*)sub, sub + i + 1);
    } else if (k != 0) {
        return 0;
    } else {
        strcpy(hsub, sub);
        sub[0] = '\0';
    }
    return 1;
}



void CreateGenList(GenList* gl,char* str){
    /*
    将广义表就看成两部分:表头(广义表第一个元素) 表尾(广义表除第一个元素的其他元素)
    */
    //先去除最外层括号 
    int n = strlen(str);
    //用于存储去掉最外层括号的str
    char* sub = (char*)malloc(sizeof(char) * (n-2));
    //用于存储表头元素 
    char* hsub = (char*)malloc(sizeof(char) * (n-2));
    assert(sub != NULL && hsub != NULL);
    strncpy(sub, str + 1,n - 1);
    sub[n - 2] = '\0';
    
    if(*gl == NULL){
        //说明当前是表头节点 
        *gl = (GLNode*)malloc(sizeof(GLNode));
        assert(*gl != NULL); 
        (*gl)->tag = HEAD;
        (*gl)->hp = (*gl)->tp = NULL;
    }
    //采用尾插法 
    GLNode *p = *gl;
    while(strlen(sub) != 0){
        p = p->tp = (GLNode*)malloc(sizeof(GLNode));
        assert(p != NULL);
        //填充数据
        p->hp = p->tp = NULL;
        
        //"1,2,3" ==> hsub="1", sub="2,3"
        //"(1,2),3,4" ==> hsub="(1,2)" sub="3,4" 
        if(separate(sub,hsub)){
            if(hsub[0] == '('){
                //说明分离出来的元素是个子表
                p->tag = CHILDLIST;
                CreateGenList(&p->hp,hsub);                
            } else {
                p->tag = ATOM;
                p->atom = atoi(hsub);
            }
        } 
    }
}

3、广义表的其他方法实现

void showGenList(GenList gl) {
    GLNode* p = gl->tp;
    printf("(");
    while (p != NULL) {
        if (p->tag == ATOM) {
            printf("%d", p->atom);
        } else if (p->tag == CHILDLIST) {
            showGenList(p->hp);
        }
        // 检查下一个节点是否存在，如果存在则打印逗号
        if (p->tp != NULL) {
            printf(",");
        }
        p = p->tp;
    }
    printf(")");
}

// 求广义表的长度 
int length(GenList gl){
    int len = 0;
    while(gl->tp != NULL){
        len++;
        gl = gl->tp;
    }
    return len;
} 
int GenListDepth(GenList gl){
    if(gl->tp == NULL)
        return 1;
    //指向广义表第一个节点 
    GLNode *p = gl->tp;
    int maxDepth = 0;
    int dep;
    while(p != NULL){
        if(p->tag == CHILDLIST) {
            // 传入广义表子表的 第一个节点 
            dep = GenListDepth(p->hp->tp);
            if(dep > maxDepth){
                maxDepth = dep;
            }    
        }
        p = p->tp;
    }
    return maxDepth + 1;
}


void freeGenList(GenList gl) {
    if (gl == NULL) return;
    GLNode* p = gl->tp;
    while (p != NULL) {
        if (p->tag == CHILDLIST) {
            freeGenList(p->hp);
        }
        GLNode* next = p->tp;
        free(p);
        p = next;
    }
    free(gl);
}

int main(){
    GenList gl;
    InitGenList(&gl);
    char* ga = "(1,2,3)";
    char* gb = "(1,(2,3))";
    char* gc = "(1,(2),3)";
    char* gd = "((1,2),3)";
    char* ge = "((1,2,3))";
    char* gf = "()";
    char* gg = "(1,(2,(3,4)),5)";
    
    CreateGenList(&gl,gg);
    showGenList(gl); 
    printf("\nLength: %d",length(gl));
    printf("\nDepth: %d",GenListDepth(gl));
    freeGenList(gl);  // 释放广义表占用的内存
    return 0;
}