H - Hard to Believe, but True!

左手的ㄟ右手 2022-03-19 06:56 92阅读 0赞

### 题目描述： ###

The fight goes on, whether to store numbers starting with their most significant digit or their least significant digit. Sometimes this is also called the “Endian War”. The battleground dates far back into the early days of computer science. Joe Stoy, in his (by the way excellent) book “Denotational Semantics”, tells following story:  
“The decision which way round the digits run is, of course, mathematically trivial. Indeed, one early British computer had numbers running from right to left (because the spot on an oscilloscope tube runs from left to right, but in serial logic the least significant digits are dealt with first). Turing used to mystify audiences at public lectures when, quite by accident, he would slip into this mode even for decimal arithmetic, and write things like 73+42=16. The next version of the machine was made more conventional simply by crossing the x-deflection wires: this, however, worried the engineers, whose waveforms were all backwards. That problem was in turn solved by providing a little window so that the engineers (who tended to be behind the computer anyway) could view the oscilloscope screen from the back.  
\[C. Strachey - private communication.\]”

You will play the role of the audience and judge on the truth value of Turing’s equations.  
Input  
The input contains several test cases. Each specifies on a single line a Turing equation. A Turing equation has the form “a+b=c”, where a, b, c are numbers made up of the digits 0,…,9. Each number will consist of at most 7 digits. This includes possible leading or trailing zeros. The equation “0+0=0” will finish the input and has to be processed, too. The equations will not contain any spaces.  
Output  
For each test case generate a line containing the word “True” or the word “False”, if the equation is true or false, respectively, in Turing’s interpretation, i.e. the numbers being read backwards.  
Sample Input  
73+42=16  
5+8=13  
10+20=30  
0001000+000200=00030  
1234+5=1239  
1+0=0  
7000+8000=51  
0+0=0  
Sample Output  
True  
False  
True  
True  
False  
False  
True  
True

##### 题意： #####

又是一堆废话，其实这个题意就是给出了一个等式。  
例如：73+42=16  
那么就求37+24=61这个等式是否成立。这样一看就很简单了。然后稍微注意一下前导0的情况。还有就是测试数据中有空格的出现。  
其实通过观察，我们会发现如果这个题从后往前算这三个数，会非常简单。而且测试数据中只有+ 这一个运算。  
AC代码：

#include"stdio.h"
    #include"string.h"
    int main()
    {
        char text[1001];
        int a,b,c,i;
        while(gets(text)!=NULL)
        {
            a=b=c=0;
            int len=strlen(text);
            for(i=len-1; text[i]!='='; i--)
            {
                if(text[i]>='0'&&text[i]<='9')
                    a=a*10+(text[i]-'0');
            }
            for(i--; text[i]!='+'; i--)
                if(text[i]>='0'&&text[i]<='9')
                    b=b*10+(text[i]-'0');
            for(i--; text[i]>=0; i--)
                if(text[i]>='0'&&text[i]<='9')
                    c=c*10+(text[i]-'0');
            if(c+b==a)
                printf("True\n");
            else
                printf("False\n");
        }
    }