1023 Have Fun with Numbers （PAT甲级）

#include 
#include 

std::string s;
int carry = 0;
int a[10] = {0};
int b[10] = {0};

int main(){
    std::cin >> s;
    for(int i = s.size() - 1; i >= 0; --i){
        a[s[i] - '0']++;
        s[i] = s[i] + s[i] - '0' + carry;
        carry = 0;
        if(s[i] > '9'){
            s[i] -= 10;
            carry = 1;
        }
        b[s[i] - '0']++;
    }
    if(carry){
        s = "1" + s;
        std::cout << "No" << std::endl << s;
        return 0;
    }
    for(int i = 0; i < 10; ++i){
        if(a[i] != b[i]){
            std::cout << "No" << std::endl << s;
            return 0;
        }
    }
    std::cout << "Yes" << std::endl << s;
    return 0;
}

题目如下：

Notice that the number 123456789 is a 9-digit number consisting exactly the numbers from 1 to 9, with no duplication. Double it we will obtain 246913578, which happens to be another 9-digit number consisting exactly the numbers from 1 to 9, only in a different permutation. Check to see the result if we double it again!

Now you are suppose to check if there are more numbers with this property. That is, double a given number with k digits, you are to tell if the resulting number consists of only a permutation of the digits in the original number.

Input Specification:

Each input contains one test case. Each case contains one positive integer with no more than 20 digits.

Output Specification:

For each test case, first print in a line "Yes" if doubling the input number gives a number that consists of only a permutation of the digits in the original number, or "No" if not. Then in the next line, print the doubled number.

Sample Input:

1234567899

Sample Output:

Yes
2469135798