Python program to find smallest number in a list

We are given a list of numbers and our task is to write a Python program to find the smallest number in given list. For the following program we can use various methods including the built-in min method, sorting the  array and returning the last element, etc.
Example: 

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

Input : list2 = [20, 10, 20, 1, 100]
Output : 1

Sorting the list to find smallest number in a list

In Ascending order

Here writing a Python program where we are sorting the entire list and then returning the first element as it’ll be the smallest element present in the list.

Python3

# Python program to find smallest
# number in a list

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

# sorting the list
list1.sort()

# printing the first element
print("Smallest element is:", list1[0])

Output: 

smallest element is: 4

In Descending order

Here we are sorting using the sort() function the entire list and then returning the last element as it’ll be the smallest element present in the list.

Python3

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

# sorting the list
list1.sort(reverse=True)

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

Output:

smallest element is: 4

Using min() Method to find smallest number in a list

Here we are using the min Method and then returning the smallest element present in the list.

Python3

# Python program to find smallest
# number in a list

# list of numbers
list1 = [10, 20, 1, 45, 99]


# printing the maximum element
print("Smallest element is:", min(list1))

Output: 

Smallest element is: 1

Find minimum list element for a user defined list

Python3

# Python program to find smallest
# 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("Smallest element is:", min(list1))

Output: 

Enter number of elements in list: 4
Enter elements: 12
Enter elements: 19
Enter elements: 11
Enter elements: 99
Smallest element is: 11

Find the smallest element in list comparing every element

Python3

# Python program to find smallest
# number in a list

l=[ int(l) for l in input("List:").split(",")]
print("The list is ",l)

# Assign first element as a minimum.
min1 = l[0]

for i in range(len(l)):

    # If the other element is min than first element
    if l[i] < min1:
        min1 = l[i] #It will change

print("The smallest element in the list is ",min1)

Input: 

List: 23,-1,45,22.6,78,100,-5

Output:

The list is ['23', '-1', '45', '22.6', '78', '100','-5']
The smallest element in the list is  -5

Using the lambda function to find smallest number in a list

Here we are using the lambda function to print the smallest number present in the list.

Python3

# Python code to print smallest element in the list

lst = [20, 10, 20, 1, 100]
print(min(lst, key=lambda value: int(value)) )

Output:

1

Using the enumerate function to find smallest number in a list

Here we are iterating over the list using the enumerate() function and returning the last element.

Python3

lst = [20, 10, 20, 1, 100]
a,i = min((a,i) for (i,a) in enumerate(lst))
print(a)

Output:

1

Using reduce function to find the smallest number in a list

Here we are iterating over the list using reduce() function and returning the smallest element.

Python

# Python code to print smallest element in the list
from functools import reduce
lst = [20, 10, 20, 15, 100]
print(reduce(min,lst) )

Output

10

Using heap:

One approach is to use a heap data structure. A heap is a complete binary tree that satisfies the heap property: the value of each node is at least as great as the values of its children. This property allows us to efficiently find the largest or smallest element in the heap in O(1) time.

To find the smallest element in a list using a heap, we can first build a min heap using the elements in the list. Then, we can simply return the root element of the heap, which will be the smallest element in the heap.

Here is an example of how this can be done in Python:

Python3

import heapq

def find_smallest(numbers):
    # Build a min heap using the elements in the list
    heap = [(x, x) for x in numbers]
    heapq.heapify(heap)

    # Return the root element (smallest element)
    _, smallest = heapq.heappop(heap)

    return smallest

# Test the function
numbers = [10, 20, 4, 45, 99]
print(find_smallest(numbers))  # Output: 4
#This code is contributed by Edula Vinay Kumar Reddy

Output

4

This approach has a time complexity of O(n log n) for building the heap and O(1) for finding the smallest element, making it more efficient than the methods mentioned in the article which have a time complexity of O(n).

Method: Using recursion

We can use recursive function to find the smallest number in the list.

Python3

def Findsmall(itr,ele,list1): #recursive function to find smallest number
  if itr == len(list1):        #base condition
    print("The smallest number in the list is " ,ele)
    return
  if list1[itr]<ele: #check the current element less than minimum or not
    ele  =  list1[itr]
  Findsmall(itr+1,ele,list1) #recursive function call
  return
#driver code
lis=[5,7,2,8,9]
ele = lis[0]
Findsmall(0,ele,lis)
#This code is contributed by Vinay Pinjala

Output

The smallest number in the list is  2

Time complexity: O(n)  It will perform n recursive calls so the time complexity  will be O(n).
Auxiliary Space: O(n) ,It will perform n recursive calls each recursive call pushed into stack so the space complexity will be O(n)

Using numpy module:

We can use numpy module to find the smallest number in the list.

Python3

#importing module
import numpy as np

#Initializing list
lis = [5, 7, 2, 8, 9]

#finding minimum value
minimum = np.min(lis)

#printing output
print("The smallest number in the list is", minimum)
#This code contributed by tvsk

Output

The smallest number in the list is 2

Time complexity: O(n), here n is the size of the input list. This is because the numpy min function iterates over each element in the list once to find the minimum value.
Auxiliary Space: O(1), as it only requires a single variable “minimum” to store the result.