【0006】数据的压缩、解压缩——时间优先、空间优先

时间优先的方式实现数据的压缩、解压缩

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// "aaaaabbbhaihualovefangfangooooooooo";    --> 5a3bhaihualovefangfang9o
char * timefastzip(char *str)
{
    int length = strlen(str);                                // 获取待压缩字符串的长度
    char *newstr = (char *)calloc(length, sizeof(char));    // 给压缩的字符串开辟内存

    char *pstr = str;
    char *pnewstr = newstr;            // 保存分配内存的首地址

    while (*pstr != '')
    {
        int charlength = 0;
        char * p = pstr;
        while (*p == *(p + 1))
        {
            charlength++;                        // 统计重复字母次数
            p++;
        }

        if (charlength == 0)
            *pnewstr++ = *pstr++;
        else
        {
            *pnewstr = charlength + 1 + '0';    // 重复字母个数转化为数值型字符
            *(pnewstr + 1) = *pstr;
            pnewstr += 2;
            pstr += charlength + 1;
        }
    }

    _recalloc(newstr, strlen(newstr), sizeof(char));        // 释放压缩的空间

    return newstr;
}

char * timefastunzip(char *str)
{
    char *newstr = (char *)calloc(10000, sizeof(char));

    char *pstr = str;
    char *pnewstr = newstr;

    while (*pstr != '')
    {
        char *p = pstr;
        if (*p >= '0'&&*p <= '9')
        {
            int length = *p - '0';
            for (int i = 0; i < length; i++)
            {
                *pnewstr++ = *(p + 1);
            }
            pstr += 2;
        }
        else
        {
            *pnewstr++ = *pstr++;
        }
    }

    _recalloc(newstr, strlen(newstr), sizeof(char));

    return newstr;
}

void main006()    
{
    char str[1024] = "aaaaabbbhaihualovefangfangooooooooo";    // 5a3bhaihualovefangfang9o

    printf("%s 
", str);
    printf("%s 
", timefastzip(str));
    printf("%s 
", timefastunzip(str));

    system("pause");
}

空间优先的方式实现数据的压缩、解压缩

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// 双指针法操作字符串
// "aaaaabbbhaihualovefangfangooooooooo";    --> 5a3bhaihualovefangfang9o
char * spacezipa(char *str)        // 压缩字符串中的a
{
    char *p1 = str;
    char *p2 = str;

    while (*p1 = *p2)
    {
        if (*p1 != 'a')
        {
            p1++;
            p2++;
        }
        else
        {
            p2++;
        }
    }

    return str;
}
char * spacezipX(char *str)        // abhaihualovefangfango
{
    char *p1 = str;
    char *p2 = str;

    while (*p1 = *p2)
    {
        int length = 1;
        while (*p1 == *p2)
        {
            p2++;
        }
        p1++;
    }

    return str;
}
char * spacezip(char *str)        // 5a3bhaihualovefangfang9o
{
    char *p1 = str;
    char *p2 = str;

    while (*p1 = *p2)
    {
        int length = 1;
        char *p3 = p2 + 1;
        while (*p1 == *p3)
        {
            p3++;
            length++;
        }

        if (length > 1)
        {
            *p1 = length + '0';
            *(p1 + 1) = *(p3 - 1);
            p1 += 2;
            p2 += length;
        }
        else
        {
            p1++;
            p2++;
        }
    }

    return str;
}

char * spaceunzip(char *str)
{
    char *p1 = str;
    char *p2 = str;

    while (*p1 = *p2)
    {
        int length = 0;
        if (*p1 >= '0'&&*p1 <= '9')
        {
            length = *p1 - '0';
        }

        if (length == 0)
        {
            p1++;
            p2++;
        }
        else
        {
            char ch = *(p1 + 1);
            for (char *p = p1 + strlen(p1); p > p1 + 1; p--)        // 5a  扣除两个字符
            {
                *(p + length - 2) = *p;
            }
            
            for (int i = 0; i < length; i++)
            {
                *(p1 + i) = ch;
            }

            p1 += length;
            p2 = p1;
        }
    }

    return str;
}

void main007()    
{
    char str[1024] = "aaaaabbbhaihualovefangfangooooooooo";    // 5a3bhaihualovefangfang9o

    printf("%s 
", str);
    printf("%s 
", spacezip(str));
    printf("%s 
", spaceunzip(str));

    system("pause");
}