Algorithms and Data Structures - Spring 2018

Homework Assignments

count in array: Write a Python function called count_in_array(A,x) that that takes an array A of numbers and a number x, and returns the number of times the value x appears in A.
Examples and testing: Test your solution using the interactive Python interpreter. If you call count_in_array(5, [7, 5, 16, 3, 10, 5, 8, 1, 29, 13, 28]), the result should be 2.
vertical histogram
Write a program that reads a list of numbers from the standard input, with one or more numbers per line, and prints a vertical histogram corresponding to those numbers. In this histogram, each number N is represented by a column of N characters "#" starting from a base-line of N dash characters "-" representing value 0. Positive numbers are represented by a column above zero while negative numbers are represented with a column below zero.
For example, with this input:
```
7 3 -2 10 5 -3 3 5 8 
```
The output must be as follows:
```
   #     
   #     
   #    #
#  #    #
#  #    #
#  ##  ##
#  ##  ##
## ## ###
## ## ###
## ## ###
---------
  #  #   
  #  #   
     #   
```
partition even/odd
Write a python function called partition_even_odd that takes an array of integers, and that changes that array in-place so that all the even elements precede all the odd elements. The change is in-place in the sense that it must be carried out just by swapping elements of the input array, in particualar without creating other arrays.
Also write a python program to test the partition_even_odd function. The program must compile an array by reading a sequence of integers from the standard input, with one or more numbers per line, then call partition_even_odd, and then print the content of the array on the standard output. For example, with this input
```
7 3 2 10 5 3 3 5 8
```
The output might be this:
```
2 10 8 7 3 5 3 3 5
```
but never this:
```
8 3 2 10 5 3 3 5 7
```