Hdoj HDU 1202 the calculation of gpa acm 202 in HDU

Miyu original, post Please note: Reprinted from __________ White House

Question address:
Http://acm.hdu.edu.cn/showproblem.php? PID = 1, 1202
Description:Problem description
At the end of each semester, everyone is busy calculating their average score. This score is directly related to scholarship evaluation. Both foreign universities calculate GPa (grade point average), also known as GPR (grade point ratio), that is, the weighted average of score points and credits represents the score of a student. How can we calculate the GPA?

Calculation method adopted by General Universities

A90 -   100   4 Point
B80 -   89   3 Point
C70 -   79   2 Point
D60 -   69   1 Point
E0 -   59   0 Point

For example, if a student takes three courses, the course subjects, credits, and scores are:
English: three credits,92Chemistry: Five credits,80Points; mathematics: Two credits, 60 points, then the GPAAlgorithmAs follows:

Subject credit score points score × points
English 3 92 4 12
Chemistry 5 80 3 15
Mathematics 2 60 1 2
Total 10 29  
29 / 10 = 2.9  
2 . 9 is a generated GPA.
Below is a listProgram.
 

Input
Contains multiple groups of data. The first row of each group contains N numbers, and the next n rows indicate a score. Each row has two real-type numbers: S, P, and S, which indicate the credits of the course, and P indicates the score of the student (percentage ). If P=-1 indicates that the student is absent and should not be taken into consideration.
 

Output
Output a row of data in each group, indicating the student's GPA. The two decimals are retained. If the GPA does not exist, output-1.
 

Sample Input
3
3 92
5 80
2 60
 

Sample output
2.90

There is no doubt that this is a question of water, but I have suffered two tragedies by wa. I noticed a sentence in the output requirement of the question:If the GPA does not exist, output-1.

When does it not exist?0! You only need to process this 0. ym.

CodeAs follows://Miyu original, post Please note: Reprinted from __________ White House

# Include < Iostream >
# Include < Iomanip >
Using   Namespace STD;
Int Hash [ 11 ] = { 0 , 0 , 0 , 0 , 0 , 0 , 1 , 2 , 3 , 4 , 4 };
Int Main ()
{
Int T;
While (CIN > T)
{
Double Total =   0 , Pnt =   0 , SCR =   0 , MLT =   0 ;
While (T -- )
{
CIN > Pnt > SCR;
If (SCR =   - 1 )
{
Continue ;
}
Total + = PNT;
MLT + = Pnt * Hash [( Int ) SCR /   10 ];
}
If (Total < 1e - 5 )
{
Cout <   - 1   < Endl;
Continue ;
}
Cout < Setprecision ( 2 ) < Setiosflags (IOs :: Fixed ) < MLT *   1.0   / Total < Endl;
}
Return   0 ;
}