51Nod - 1770 Counting Numbers

Count  a a a ⋯ a a a  n a _ ×b aaa ⋯ aaa⏟n  how many numbers d are in the results of a × b, a, b, d are all single digits.

Example explanation:

3333333333*3=9999999999, there are 10 9s in it.

Input multiple sets of test data. 
The first line has an integer T, which represents the number of test data. (1≤T≤5000) 
Next there are T lines, each line represents a set of test data, there are 4 integers a, b, d, n. (1≤a, b≤9, 0≤d≤9, 1≤n≤10^9) Output For each set of data, output an integer on one line to represent the answer. Sample Input

2
3 3 9 10
3 3 0 10

Sample Output

10
0

Analog Multiplication

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
intmain()
{
    int t;
    int a,b,d,n;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d%d%d",&a,&b,&d,&n);
        int rest=0,next=0;
        int res=-1;
        int years;
        int sum=0;
        for(int i=0; i<n; i++)
        {
            ans=a*b+next;
            next=ans/10;
            rest=ans%10;
            if(ans==res)
            {
                if(rest==d)
                    sum+=n-i;
                break;
            }
            res=ans;
            if(rest==d)
                sum++;
        }
        if(next!=0&&next==d)
            sum++;
        printf("%d\n",sum);
    }
}