Python program to find largest number in a list

Given a list of numbers, the task is to write a Python program to find the largest number in given list. 

Examples:

Input : list1 = [10, 20, 4]
Output : 20

Input : list2 = [20, 10, 20, 4, 100]
Output : 100

Method 1: Sort the list in ascending order and print the last element in the list. 

Python3

# Python program to find largest
# number in a list

# list of numbers
list1 = [10, 20, 4, 45, 99]

# sorting the list
list1.sort()

# printing the last element
print("Largest element is:", list1[-1])

Output

Largest element is: 99

Time Complexity: O(nlogn)
Auxiliary Space: O(1)

Method 2: Using max() method 

Python3

# Python program to find largest
# number in a list

# list of numbers
list1 = [10, 20, 4, 45, 99]


# printing the maximum element
print("Largest element is:", max(list1))

Output

Largest element is: 99

Time complexity : O(n)
Auxiliary Space : O(1)

Method 3: Find max list element on inputs provided by user 

Python3

# Python program to find largest
# number in a list

# creating empty list
list1 = []

# asking number of elements to put in list
num = int(input("Enter number of elements in list: "))

# iterating till num to append elements in list
for i in range(1, num + 1):
    ele = int(input("Enter elements: "))
    list1.append(ele)

# print maximum element
print("Largest element is:", max(list1))

Output:

Enter number of elements in list: 4
Enter elements: 12
Enter elements: 19
Enter elements: 1
Enter elements: 99
Largest element is: 99

Time complexity : O(n)
Auxiliary Space : O(1)

Method 4: Without using built-in functions in python: 

Python3

# Python program to find largest
# number in a list


def myMax(list1):

    # Assume first number in list is largest
    # initially and assign it to variable "max"
    max = list1[0]
# Now traverse through the list and compare
    # each number with "max" value. Whichever is
    # largest assign that value to "max'.
    for x in list1:
        if x > max:
            max = x

    # after complete traversing the list
    # return the "max" value
    return max


# Driver code
list1 = [10, 20, 4, 45, 99]
print("Largest element is:", myMax(list1))

Output

Largest element is: 99

Time complexity : O(n)
Auxiliary Space : O(1)

Method 5: Use the max() and def functions to find the largest element in a given list. The max() function prints the largest element in the list.  

Python3

# Python code to find the largest number
# in a list


def maxelement(lst):
    # displaying largest element
    # one line solution
    print(max(lst))


# driver code
# input list
lst = [20, 10, 20, 4, 100]
# the above input can also be given as
# lst = list(map(int, input().split()))  # -> taking input from the user
maxelement(lst)

Output

100

Time complexity : O(n)
Auxiliary Space : O(1)

Method: Using the lambda function

Python3

# python code to print largest element in the list

lst = [20, 10, 20, 4, 100]
print(max(lst, key=lambda value: int(value)) )

Output

100

Time complexity : O(n)
Auxiliary Space : O(n), where n is length of list.

Method: Using reduce function

Python3

from functools import reduce
lst = [20, 10, 20, 4, 100]
largest_elem = reduce(max, lst)
print(largest_elem)

Output

100

Time Complexity: O(n)
Auxiliary Space: O(1)

Method: Using recursion

Python3

#Function to find the largest element in the list
def FindLargest(itr,ele,list1):
  if itr == len(list1): #Base condition
    print("Largest element in the list is: ", ele)
    return
  if ele < list1[itr]: #check max condition
    ele = list1[itr]
  FindLargest(itr+1,ele,list1) #recursive solution
  return
list1=[2,1,7,9,5,4]
FindLargest(0,list1[0],list1)

Output

Largest element in the list is:  9

Time Complexity: O(n)
Auxiliary Space: O(n)