「NOIP」「2012」Vigenère密码

题目：http://www.tsinsen.com/ViewGProblem.page?gpid=A1366

 

题目解析：随后

 

代码：

/*
 * =====================================================================================
 *
 *       Filename:  Noip2012mima.c
 *
 *    Description:  RT
 *
 *        Version:  1.0
 *        Created:  2014-05-20 14:42:40
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Rainboy (mn), 597872644@qq.com
 *        Company:  NONE
 *
 * =====================================================================================
 */
#include <stdio.h>
#include <string.h>
char mimabiao[26][26];
char mishi[100],miwen[1000];

int main(int argc, const char *argv[])
{
    //第一步 生成密码表
    char a ='A';
    int i,j,k,l,mishilength,miwenlength;

    for (i = 0; i < 26; i++)  //竖行
    {
        a = 'A'+i;

        for (j = 0; j < 26; j++)  // 横行
        {
            mimabiao[i][j] = a;

            if(++a > 'Z')
                a = 'A';
        }
    }

    //注意 要保持明文中的字母大小写
    l=0;//秘钥 现在所在的位置
    scanf("%s",mishi);
    mishilength =strlen(mishi);
    scanf("%s",miwen);
    miwenlength = strlen(miwen);

    //把秘钥转成 大写
    for (i = 0; i < mishilength; i++)
    {
        mishi[i]=toupper(mishi[i]);
    }

    for (i = 0; i < miwenlength; i++)
    {
        if(miwen[i] < 'a')//判断大小写字母 'a' >'A'
            for(j = 0; j < 26; j++)
            {
                if(mimabiao[mishi[l]-'A'][j] == miwen[i])
                {
                    printf("%c",'A'+j);
                    break;
                }
            }

        else

            for(j = 0; j < 26; j++)

                if(mimabiao[mishi[l]-'A'][j] == toupper(miwen[i]))
                {
                    printf("%c",'a'+j);
                    break;
                }


        if (++l >= mishilength)
        {
            l=0;
        }

    }

    return 0;
}