The goal of the question is very simple, which is to find the sum of two positive integers A, Bwhere Aboth Bsums are in the interval [1,1000]. Slightly troublesome, the input is not guaranteed to be two positive integers.
Input format:
AInput gives and on one line B, separated by spaces. The problem is Athat Bthe sum is not necessarily a positive integer that meets the requirements. Sometimes it may be a number that is out of range, a negative number, a real number with a decimal point, or even a bunch of garbled characters.
Note: We regard the first space that appears in the input as the separation of Aand B. The title guarantees at least one space and Bnot an empty string.
Output format:
If the input is indeed two positive integers, the A + B = 和output is formatted. If an input does not meet the requirements, it is output at the corresponding position ?, obviously at this time and also ?.
Example 1:
123 456
Output sample 1:
123 + 456 = 579
Input sample 2:
22. 18
Output sample 2:
? + 18 = ?
Input sample 3:
-100 blabla bla...33
Output sample 3:
? + ? = ?important point:
- A and B are positive integers in the range of [1,1000]
- A can be an empty string
AC code
#include<bits/stdc++.h>
using namespace std;
int f,idx;
string s,a,b;
signed main()
{
getline(cin,s);
idx=s.find(" ");
a=s.substr(0,idx);
b=s.substr(idx+1);
// 正则表达式[1-9][0-9]*表示第一个字符为1-9的数字（可以排除只有0或者前缀有0的情况），后面的字符可以有0个或多个0-9的数字
if(regex_match(a,regex("[1-9][0-9]*"))&&stoi(a)<=1000) cout<<stoi(a),f++;
else cout<<"?";
cout<<" + ";
if(regex_match(b,regex("[1-9][0-9]*"))&&stoi(b)<=1000) cout<<stoi(b),f++;
else cout<<"?";
cout<<" = ";
if(f==2) cout<<stoi(a)+stoi(b);
else cout<<"?";
return 0;
}