# Easy Coding Contest-13 Editorial

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### Easy Coding Contest-13 Editorial

Problem A: Bit Need
Problem Setter: Bishal Gautam

In this problem, you have given an integer number , you have to find the minimum total number of bits needed to represent it in binary number system.
So, if we convert the given integer to binary number without leading zeros and count the length of binary number, then we can get the answer.
The special care should be taken with 0.
For binary conversion, we can divide the given integer with number 2 until it becomes zero.

Problem B: Prime and Even-Odd
Problem Setter: Mohibur Rahman

In this problem , you have given N and M, your task is to find whether the summation of N-th and M-th prime number is even or odd.
In all prime number 2 is only even prime number and others are odd.So, the logic is simple if one of two input number is 1 and another number is whatever except 1 then the result is Odd,Otherwise even.
Because the first number is 2 and it's only even prime number and others are odd ,and we all know that sum of an even and an odd number is always odd. On the other hand, the sum of any two odd number is even and also the sum of two even number is even.

Problem C: Power Of 5
Problem Setter: Bishal Gautam

In this problem, you are given an integer, say N, your task is to determine whether this integer can be represented as a non-negative power of 5. So, you can easily check this by diving input with 5 till it is divisible by 5 and if we end with integer 1 finally, then, this number is divisible by 5. because, every number which is power of 5 can be represented as many multiplications of 5s i.e 5*5*...*5.
Note: Special care should be taken for 1, since 5^0 =1 and also we may have to take care of 0 while checking for divisibility.

Problem D: Decrypt The Secret Message
Problem Setter: Mir Lutfur Rahman

In this problem,you have to find out the occurrence of characters and find the maximum one each time for build each word. Use space to separate two words.
Just count the characters and store them after that sort them and according to the word length print them serially and put space between two words.

Problem E:Fibonacci Divisor
Problem Setter: Kazi Sohan

In this problem, you have to find the number of fibonacci numbers which is divisible by another fibonacci number.
We add the previous two fibonacci numbers to get the next one.

let, (n-1)th fibonacci number is b.
nth fibonacci number is x
Code: Select all
`      so, (n+1)th fibonacci number is =x+b      (n+2)th fibonacci number is      =x+x+b=2*x+b      (n+3)th fibonacci number is      =(x+b)+(2*x+b)=(3*x+2*b)      .........................................................................................      .........................................................................................      (n+n)th fibonacci number is     = ( (n+1)th fibonacci number )*x + ( (nth fibonacci number) * b ) `

which is divisible by nth fibonacci number

So every nth fibonacci number will be divisible by nth fibonacci number

Hence, answer will be equal to k/n.

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