Function returns the smallest integer value greater than or equal to value of parameter passed to it

This question doesn't really need another answer, but there is a solution that has not been proposed yet, that I believe to be faster than what's been presented so far.

As others have pointed out, we know the answer lies in the range [1, len(A)+1], inclusively. We can turn that into a set and take the minimum element in the set difference with A. That's a good O(N) solution since set operations are O(1).

However, we don't need to use a Python set to store [1, len(A)+1], because we're starting with a dense set. We can use an array instead, which will replace set hashing by list indexing and give us another O(N) solution with a lower constant.

def minpositive(a): # the "set" of possible answer - values_found[i-1] will tell us whether i is in a values_found = [False] * (len(a)+1) # note any values in a in the range [1, len(a)+1] as found for i in a: if i > 0 and i <= len(a)+1: values_found[i-1] = True # extract the smallest value not found for i, found in enumerate(values_found): if not found: return i+1

We know the final for loop always finds a value that was not marked, because it has one more element than a, so at least one of its cells was not set to True.

Introduction to Functions in Python

A function allows you to define a reusable block of code that can be executed many times within your program.

Functions allow you to create more modular and DRY solutions to complex problems.

While Python already provides many built-in functions such as print() and len(), you can also define your own functions to use within your projects.

One of the great advantages of using functions in your code is that it reduces the overall number of lines of code in your project.

Syntax

In Python, a function definition has the following features:

The keyword def
a function name
paranthesis’()’, and within paranthesis input parameters,although the input parameters are optional.
a colon ’:’
some block of code to execute
a return statement (optional)

# a function with no parameters or returned values def sayHello(): print("Hello!") sayHello() # calls the function, 'Hello!' is printed to the console # a function with a parameter def helloWithName(name): print("Hello " + name + "!") helloWithName("Ada") # calls the function, 'Hello Ada!' is printed to the console # a function with multiple parameters with a return statement def multiply(val1, val2): return val1 * val2 multiply(3, 5) # prints 15 to the console

Functions are blocks of code that can be reused simply by calling the function. This enables simple, elegant code reuse without explicitly re-writing sections of code. This makes code both more readable, makes for easier debugging, and limits typing errors.

Functions in Python are created using the def keyword, followed by a function name and function parameters inside parentheses.

A function always returns a value,The return keyword is used by the function to return a value, if you don’t want to return any value, the default value None will returned.

The function name is used to call the function, passing the needed parameters inside parentheses.

# this is a basic sum function def sum(a, b): return a + b result = sum(1, 2) # result = 3

You can define default values for the parameters, that way Python will interpretate that the value of that parameter is the default one if none is given.

def sum(a, b=3): return a + b result = sum(1) # result = 4

You can pass the parameters in the order you want, using the name of the parameter.

result = sum(b=2, a=2) # result = 4

However, it is not possible to pass a keyword argument before a non-keyword one

result = sum(3, b=2) #result = 5 result2 = sum(b=2, 3) #Will raise SyntaxError

Functions are also Objects, so you can assign them to a variable, and use that variable like a function.

s = sum result = s(1, 2) # result = 3

Notes

If a function definition includes parameters, you must provide the same number of parameters when you call the function.

print(multiply(3)) # TypeError: multiply() takes exactly 2 arguments (0 given) print(multiply('a', 5)) # 'aaaaa' printed to the console print(multiply('a', 'b')) # TypeError: Python can't multiply two strings

The block of code that the function will run includes all statements indented within the function.

def myFunc(): print('this will print') print('so will this') x = 7 # the assignment of x is not a part of the function since it is not indented

Variables defined within a function only exist within the scope of that function.

def double(num): x = num * 2 return x print(x) # error - x is not defined print(double(4)) # prints 8

Python interprets the function block only when the function is called and not when the function is defined.So even if the function definition block contains some sort of error, the python interpreter will point that out only when the function is called.

Now let's look at some specific functions with examples.

max() function

max() is a built-in function in Python 3. It returns the largest item in an iterable or the largest of two or more arguments.

Arguments

This function takes two or more numbers or any kind of iterable as an argument. While giving an iterable as an argument we must make sure that all the elements in the iterable are of the same type. This means that we cannot pass a list which has both string and integer values stored in it. Syntax: max(iterable, *iterables[,key, default]) max(arg1, arg2, *args[, key])

Valid Arguments:

max(2, 3) max([1, 2, 3]) max('a', 'b', 'c')

Invalid Arguments:

max(2, 'a') max([1, 2, 3, 'a']) max([])

Return Value

The largest item in the iterable is returned. If two or more positional arguments are provided, the largest of the positional arguments is returned. If the iterable is empty and default is not provided, a ValueError is raised.

Code Sample

print(max(2, 3)) # Returns 3 as 3 is the largest of the two values print(max(2, 3, 23)) # Returns 23 as 23 is the largest of all the values list1 = [1, 2, 4, 5, 54] print(max(list1)) # Returns 54 as 54 is the largest value in the list list2 = ['a', 'b', 'c' ] print(max(list2)) # Returns 'c' as 'c' is the largest in the list because c has ascii value larger then 'a' ,'b'. list3 = [1, 2, 'abc', 'xyz'] print(max(list3)) # Gives TypeError as values in the list are of different type #Fix the TypeError mentioned above first before moving on to next step list4 = [] print(max(list4)) # Gives ValueError as the argument is empty

Run Code

Official Docs

min() function

min() is a built-in function in Python 3. It returns the smallest item in an iterable or the smallest of two or more arguments.

Arguments

Valid Arguments:

min(2, 3) min([1, 2, 3]) min('a', 'b', 'c')

Invalid Arguments:

min(2, 'a') min([1, 2, 3, 'a']) min([])

Return Value

The smallest item in the iterable is returned. If two or more positional arguments are provided, the smallest of the positional arguments
is returned. If the iterable is empty and default is not provided, a ValueError is raised.

Code Sample

print(min(2, 3)) # Returns 2 as 2 is the smallest of the two values print(min(2, 3, -1)) # Returns -1 as -1 is the smallest of the two values list1 = [1, 2, 4, 5, -54] print(min(list1)) # Returns -54 as -54 is the smallest value in the list list2 = ['a', 'b', 'c' ] print(min(list2)) # Returns 'a' as 'a' is the smallest in the list in alphabetical order list3 = [1, 2, 'abc', 'xyz'] print(min(list3)) # Gives TypeError as values in the list are of different type #Fix the TypeError mentioned above first before moving on to next step list4 = [] print(min(list4)) # Gives ValueError as the argument is empty

Run Code

Official Docs

divmod() function

divmod() is a built-in function in Python 3, which returns the quotient and remainder when dividing the number a by the number b. It takes two numbers as arguments a & b. The argument can’t be a complex number.

Argument

It takes two arguments a & b - an integer, or a decimal number.It can’t be a complex number.

Return Value

The return value will be the pair of positive numbers consisting of quotient and remainder obtained by dividing a by b. In case of mixed operand types, rules for binary arithmetic operators will be applied.
For Integer number arguments, return value will be same as (a // b, a % b).
For Decimal number arguments, return value will be same as (q, a % b), where q is usually math.floor(a / b) but may be 1 less than that.

Code Sample

print(divmod(5,2)) # prints (2,1) print(divmod(13.5,2.5)) # prints (5.0, 1.0) q,r = divmod(13.5,2.5) # Assigns q=quotient & r= remainder print(q) # prints 5.0 because math.floor(13.5/2.5) = 5.0 print(r) # prints 1.0 because (13.5 % 2.5) = 1.0

REPL It!

Official Docs

Hex(x) function

hex(x) is a built-in function in Python 3 to convert an integer number to a lowercase hexadecimal string prefixed with “0x”.

Argument

This function takes one argument, x, that should be of integer type.

Return

This function returns a lowercase hexadecimal string prefixed with “0x”.

Example

print(hex(16)) # prints 0x10 print(hex(-298)) # prints -0x12a print(hex(543)) # prints 0x21f

Run Code

Official Documentation

len() function

len() is a built-in function in Python 3. This method returns the length (the number of items) of an object. It takes one argument x.

Arguments

It takes one argument, x. This argument may be a sequence (such as a string, bytes, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).

Return Value

This function returns the number of elements in the argument which is passed to the len() function.

Code Sample

list1 = [123, 'xyz', 'zara'] # list print(len(list1)) # prints 3 as there are 3 elements in the list1 str1 = 'basketball' # string print(len(str1)) # prints 10 as the str1 is made of 10 characters tuple1 = (2, 3, 4, 5) # tuple print(len(tuple1)) # prints 4 as there are 4 elements in the tuple1 dict1 = {'name': 'John', 'age': 4, 'score': 45} # dictionary print(len(dict1)) # prints 3 as there are 3 key and value pairs in the dict1

Run Code

Official Docs

Ord function

ord() is a built-in function in Python 3, to convert the string representing one Unicode character into integer representing the Unicode code of the character.

Examples:

>>> ord('d') 100 >>> ord('1') 49

chr function

chr() is a built-in function in Python 3, to convert the integer representing the Unicode code into a string representing a corresponding character.

Examples:

>>> chr(49) '1'

One thing is to be noted that, if the integer value passed to chr() is out of range then, a ValueError will be raised.

>>> chr(-10) 'Traceback (most recent call last): File "<pyshell#24>", line 1, in <module> chr(-1) ValueError: chr() arg not in range(0x110000)'

input() functions

Many a time, in a program we need some input from the user. Taking inputs from the user makes the program feel interactive. In Python 3, to take input from the user we have a function input(). If the input function is called, the program flow will be stopped until the user has given an input and has ended the input with the return key. Let’s see some examples:

When we just want to take the input:

This will just give a prompt without any message

inp = input()

Run Code

To give a prompt with a message:

promptwithmessage = input(’‘)

_

The ’_’ in the output is the prompt

Run Code

3. When we want to take an integer input:

number = int(input('Please enter a number: '))

Run Code

If you enter a non integer value then Python will throw an error ValueError. So whenever you use this, please make sure that you catch it too. Otherwise, your program will stop unexpectedly after the prompt.

number = int(input('Please enter a number: ')) # Please enter a number: as # Enter a string and it will throw this error # ValueError: invalid literal for int() with base 10 'as'

4. When we want a string input:

string = str(input('Please enter a string: '))

Run Code

Though, inputs are stored by default as a string. Using the str() function makes it clear to the code-reader that the input is going to be a ‘string’. It is a good practice to mention what type of input will be taken beforehand.

Official Docs

How to call a function in Python

A function definition statement does not execute the function. Executing (calling) a function is done by using the name of the function followed by parenthesis enclosing required arguments (if any).

>>> def say_hello(): ... print('Hello') ... >>> say_hello() Hello

The execution of a function introduces a new symbol table used for the local variables of the function. More precisely, all variable assignments in a function store the value in the local symbol table; whereas variable references first look in the local symbol table, then in the local symbol tables of enclosing functions, then in the global symbol table, and finally in the table of built-in names. Thus, global variables cannot be directly assigned a value within a function (unless named in a global statement), although they may be referenced.

>>> a = 1 >>> b = 10 >>> def fn(): ... print(a) # local a is not assigned, no enclosing function, global a referenced. ... b = 20 # local b is assigned in the local symbol table for the function. ... print(b) # local b is referenced. ... >>> fn() 1 20 >>> b # global b is not changed by the function call. 10

The actual parameters (arguments) to a function call are introduced in the local symbol table of the called function when it is called; thus, arguments are passed using call by value (where the value is always an object reference, not the value of the object). When a function calls another function, a new local symbol table is created for that call.

>>> def greet(s): ... s = "Hello " + s # s in local symbol table is reassigned. ... print(s) ... >>> person = "Bob" >>> greet(person) Hello Bob >>> person # person used to call remains bound to original object, 'Bob'. 'Bob'

The arguments used to call a function cannot be reassigned by the function, but arguments that reference mutable objects can have their values changed:

>>> def fn(arg): ... arg.append(1) ... >>> a = [1, 2, 3] >>> fn(a) >>> a [1, 2, 3, 1]

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What function returns the smallest integer value greater than or equal to value of parameter passed to it?

ceil() The Math. ceil() function always rounds up and returns the smaller integer greater than or equal to a given number.

What returns the smallest integer greater than or equal to a decimal number?

ceil method is used to return the smallest integer greater than or equal to a given number. The ceil() is always used as Math.

Which number function returns the largest integer value that is equal to or less than a number floor () Celi () trunc () MOD ()?

floor() The Math. floor() function always rounds down and returns the largest integer less than or equal to a given number.

Which member function returns the largest integer value that is equal to or less than a number?

Ceil and Floor functions in C++ In mathematics and computer science, the floor and ceiling functions map a real number to the greatest preceding or the least succeeding integer, respectively. floor(x) : Returns the largest integer that is smaller than or equal to x (i.e : rounds downs the nearest integer).