标签：Addition writes flag Codeforces int Wrong result answer sum
| Codeforces Round #762 (Div. 3) |
|---|
Tanya is learning how to add numbers, but so far she is not doing it correctly. She is adding two numbers aa and bb using the following algorithm:
- If one of the numbers is shorter than the other, Tanya adds leading zeros so that the numbers are the same length.
- The numbers are processed from right to left (that is, from the least significant digits to the most significant).
- In the first step, she adds the last digit of aa to the last digit of bb and writes their sum in the answer.
- At each next step, she performs the same operation on each pair of digits in the same place and writes the result to the left side of the answer.
For example, the numbers and
Tanya adds up as follows:
- calculates the sum of 6+5=11and writes 11 in the answer.
- calculates the sum of 3+6=9 and writes the result to the left side of the answer to get 911.
- calculates the sum of 2+4=6 and writes the result to the left side of the answer to get 6911.
- calculates the sum of 7+3=10, and writes the result to the left side of the answer to get 106911.
- calculates the sum of 1+0=11+0=1 and writes the result to the left side of the answer and get 1106911.
As a result, she gets 1106911.
You are given two positive integers aa and ss. Find the number such that by adding
and
as described above, Tanya will get
. Or determine that no suitable
exists.
Input
The first line of input data contains an integer (1≤t≤10000) — the number of test cases.
Each test case consists of a single line containing two positive integers aa and ss (1≤a<s≤10^18) separated by a space.
Output
For each test case print the answer on a separate line.
If the solution exists, print a single positive integer . The answer must be written without leading zeros. If multiple answers exist, print any of them.
If no suitable number exists, output -1.
Example
input
6 17236 1106911 1 5 108 112 12345 1023412 1 11 1 20
output
3465 4 -1 90007 10 -1
Note
The first test case is explained in the main part of the statement.
In the third test case, we cannot choose bb that satisfies the problem statement.
这道题应该要拆开各个数位上的数分别来算，以下称各个位数为a[i],b[i],s[j]。
我们不难发现，有的a[i]+b[i]后为两位数，有的为一位数，其中和为一位数得到的s[j]>=a[i],和为两位数的s[j-1]*10+s[j]<a[i],我们可以依据这个思路来写代码。
其中还有两种非法的输入使得输入后无法得到相应的b：
现在上代码。
#include <stdio.h>
#include <string.h>
int main(){
char a[30],s[30],b[30];
int t;
scanf("%d",&t);//读入重复的次数。
while(t--){
memset(a,0,sizeof(a));//对字符串进行初始化。
memset(b,0,sizeof(b));
memset(s,0,sizeof(s));
scanf("%s %s",a,s);
int la=strlen(a);
int ls=strlen(s);
int i=la-1,j=ls-1,k=0,flag=1;//i、j分别是a、s的末位元素序号，flag判断输入是否合法。
while(i>=0){
if(a[i]>s[j]){ //这种情况是a[i]+b[i]>=10。
if(s[j-1]!='1'){ //判断是否合法。
flag=0;
break;
}if(flag==0)break;
b[k]=s[j]-a[i]+10;
i--;
j-=2;
k++;
}else if(a[i]<=s[j]){ //这种情况是a[i]+b[i]<10。
b[k]=s[j]-a[i];
i--;
j--;
k++;
}
if(j<0&&i>=0){ //判断是否合法。
flag=0;
break;
}
}
k=k-1;
if(flag==0)printf("-1\n");
if(flag==1){
if(j==-1){
//此时i也等于-1，这种情况是进行多次这种操作后，a、s的元素恰好都用完。
while(b[k]==0){ //去除前导0
k--;
}
for(k;k>=0;k--){ // 逆序输出b。
printf("%d",b[k]);
}
printf("\n");
}else {
//这种情况是进行多次这种操作后，a的元素合法肯定用完，s的元素还有剩余。
for(int v=0;v<=j;v++){ //先把s的剩余元素正序输出。
printf("%c",s[v]);
}
for(;k>=0;k--){ //再倒序输出b。
printf("%d",b[k]);
}
printf("\n");
}
}
}
return 0;
}
标签：Addition,writes,flag,Codeforces,int,Wrong,result,answer,sum 来源： https://blog.csdn.net/m0_61978392/article/details/122059449
本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享； 2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关； 3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关； 4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除； 5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。