Calculating paystring for loan data - c++

Question

Example:
Input: cpi = 100.0, payments = [100.0, 94.0, 90.0, 100.0, 200.0, 100.0, 100.0, 100.0, 100.0, 100.0, 100.0, 100.0 ]
Output: paystring = [0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]
Explanation: Since the first payment was 100.0 and that is greater than or equal to cpi - 5.0 (95.0) then the first element in the output is 0. Then the next element is 1 since 94.0 is less than cpi - 5.0 (95.0) i.e. missed a payment, then since the next element 90.0 is less than cpi - 5.0 (95.0) i.e. missed another payment than now we are at 2 (or 2 total missed payments). Then in the next element we had 100 then that counts as 1 payment made so now we made that payment that was due but we still didn't cover the other two payments from the prior month so we are still at 2. Then the process continues.
I have this so far:
double cpi = 100.0;
std::vector<double> payments = { 100.0, 94.0, 90.0, 100.0, 200.0, 300.0, 100.0, 100.0, 100.0, 100.0, 100.0, 100.0 };
std::vector<int> paystring(payments.size(), 0);
int count = 0;
for (int i = 0; i < payments.size(); ++i) {
if (payments[i] <= cpi - 5.0) {
paystring[i] = ++count;
}
else {
paystring[i] = count;
}
}
for (auto it : paystring)
std::cout << it << " ";
Although, this is not correct since it fails to update count when I made lets say the full payment or more than the due amount (cpi). I just want to know what I need to change in my logic to make this work. Let me know if the example provided is unclear.
For example say I have
Input: cpi = 100.0, payments = [100.0, 94.0, 90.0, 100.0, 200.0, 100.0, 300.0, 100.0, 100.0, 100.0, 100.0, 100.0 ]
Output: [0, 1, 2, 2, 1, 0, 0, 0, 0, 0, 0, 0]
But I get
[0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]
Here is a few more examples that are correct:

Answer 1

You have a condition that if payment is too low, penalty is added, the customer is one month behind.
Add another condition: If over payment is made, for example $200, you want to give customer credit, that puts the customer one month ahead. Then add a condition that the customer is not ahead by a negative count.
std::vector<double> payments = {
100, 94, 90, 100, 200, 100, 300, 100, 100, 100, 100, 100
//"0 1 1 0 -1 0 -2 0 0 0 0 0 <-penalty
//"0 1 2 2 1 1 0 0 0 0 0 0 <-penalty sum
};
double cpi = 100.0;
for(int i = 0; i < payments.size(); ++i)
{
double payment = payments[i];
if(payment <= (cpi - 5.0))
{
//one month behind on payment
count++;
}
while((payment > cpi) && count)
{
//customer made large payment.
//allow count to decrease.
//but count cannot be less than zero
count--;
payment -= cpi;
}
paystring[i] = count;
}
Ouput for 100, 94, 90, 100, 200, 100, 100, 100, 100, 100, 100, 100:
0 1 2 2 2 2 2 2 2 2 2 2 //expected output
0 1 2 2 1 1 1 1 1 1 1 1 //result
Ouput for 100, 94, 90, 100, 200, 100, 300, 100, 100, 100, 100, 100:
0 1 2 2 1 0 0 0 0 0 0 0 //expected output
0 1 2 2 1 1 0 0 0 0 0 0 //result
My output is not the same, maybe the expected output is incorrect or you left something out. Note the 6th payment is 100, so there shouldn't be any change for that index.