水题------找准字符串，输出前一项

common typing error is to place thehands on the keyboard one row to theright of the correct position. So `Q' istyped as `W' and `J' is typed as `K' andso on. You are to decode a message typed in this manner.

Input

Input consists of several lines of text. Each line may contain digits, spaces, upper case letters (exceptQ,A,Z), or punctuation shown above [except back-quote (`)]. Keys labelled with words [Tab,BackSp,Control, etc.] are not represented in the input.

Output

You are to replace each letter or punction symbol by the one immediately to its left on the `QWERTY'keyboard shown above. Spaces in the input should be echoed in the output.Sample InputO S, GOMR YPFSU/Sample OutputI AM FINE TODAY.

题解：该题是假设输入一个键盘上的字符，如果该字符左侧是非输出字符，则输出该字符；否则，输出其左侧字符

解析：键盘上字符过多，可以考虑到将键盘上的字符改写成字符串，然后再找出该字符序数是否在字符串中（该题不考虑Q，A，Z，如果考虑的话建议另设一个字符串）

   字符串的定义方式

       1.char s[]="`1234567890-=QWERTYUIOP[]\\ASDFGHJKL;'ZXCVBNM,./";//建议第一种，第二种还需考虑转义序列

       2.char ch1[50]={'`','1','2','3','4','5','6','7','8','9','0','-','=','Q','W','E','R','T','Y','U','I','O','P','[',']','\\','A','S','D','F','G','H','J','K','L',';','\'','Z','X','C','V','B','N','M',',','.','/'};
ac代码：

#include<iostream>
#include<cstdio>
char ch1[50]={'`','1','2','3','4','5','6','7','8','9','0','-','=','Q','W','E','R','T','Y','U','I','O','P','[',']','\\','A','S','D','F','G','H','J','K','L',';','\'','Z','X','C','V','B','N','M',',','.','/'};
using namespace std;
int main()
{
    char ch,flag;
    while((ch=getchar())!=EOF)
    {
        flag=1;
        for(int i=1;ch1[i]!=0;i++)
        {
            if(ch1[i]==ch)
            {
               flag=0;
               cout<<ch1[i-1];
            }
        }
        if(flag==1)
            cout<<ch;
    }
    return 0;
}
改进后：

#include<cstdio>
#include<iostream>
using namespace std;
int main()
{
    int i,ch;
    char s[]="`1234567890-=QWERTYUIOP[]\\ASDFGHJKL;'ZXCVBNM,./";
    while((ch=getchar())!=EOF)
    {
        for(i=1;s[i]&&s[i]!=ch;i++);//先找再判
        if(s[i])  printf("%c",s[i-1]);
        else putchar(ch);
    }
    return 0;
}