8891. Exactly one condition out of two

For a given integer n, print “YES” if exactly one of the following conditions is satisfied, and “NO” otherwise:

· n is an even number;

· n is a negative number and divisible by three.

Input. One single integer n.

Output. Print “YES” or “NO” depending on whether the specified conditions are satisfied.

Sample input 1	Sample output 1
22	YES
Sample input 2	Sample output 2
7	NO

SOLUTION

conditional statement

Algorithm analysis

The variable flag will be used to count the number of satisfied conditions. Initially, it is assigned a value of 0.

· If the number n is even, increment flag by 1;

· If the number n is negative and divisible by three, also increment flag by 1.

If flag = 1, exactly one condition is satisfied, so print “YES”. Otherwise, print “NO”.

Example

Let n = 22. The number is even. It is not negative and divisible by 3. Thus, only one condition is satisfied. The answer is “YES”.

Algorithm implementation

Read the input number n.

scanf("%d", &n);

Check two conditions. If a condition is satisfied, increment the value of the variable flag by 1.

flag = 0;

if (n % 2 == 0) flag++;

if (n < 0 && n % 3 == 0) flag++;

Based on the value of flag, print the result.

if (flag == 1) puts("YES");

else puts("NO");

Python implementation

Read the input number n.

n = int(input())

Check two conditions. If a condition is satisfied, increment the value of the variable flag by 1.

flag = 0

if n % 2 == 0:

flag += 1

if n < 0 and n % 3 == 0:

flag += 1

Based on the value of flag, print the result.

if flag == 1:

print("YES")

else:

print("NO")