CS302 Midterm Exam - October 14, 2014 - Page 3

Do your answers on the answer sheets provided. When you write code, you do not need to have "include" or "using" statements.

Question 5

Your job is to write the procedure int RB(int r, int b, vector <int> &N). The procedure works as follows. Each element of N is a number of balls, which are either all red or all blue. The problem is, you don't know which color they are. Your program should return 1 if it is possible for the vector to represent excaly r red balls and b blue balls. It should return 0 if it is impossible.

For example, RB(6, 7, { 4, 2, 4, 3 }) should return 1, and RB(6, 8, { 4, 2, 4, 3 }) should return 0. RB(6, 7, { 4, 4, 4, 1 }) should return 0 as well.

Constraint #1: N will have a maximum of 20 elements.
Constraint #2: Each element of N will be less than 200,000,000.
Constraint #3: No constraints on r or b.

Before writing this procedure, I want you to do the following:

Outline your solution in English, rather than writing code.
If this were a topcoder problem, N's size could not be much bigger than this. Maybe 21 or 22. Why?
Finally, code up your solution.

Scratch Space is Below (You may find the following useful):

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