Python | Find smallest element greater than K

Last Updated : 26 Nov, 2018

Given a list, write a Python program to find the smallest number which is greater than a specific element K.

Let’s see all the approaches to solve this problem, from naive to one-liners so that they can be used in programming whenever required.

Method #1 : Naive Method
Using loop we keep on re-initializing the named variable if we find the element smaller than the previous value than the named variable and greater than K.

# Python3 code to demonstrate 
# smallest number greater than K
# using naive method 
  
# Initializing list 
test_list = [1, 4, 7, 5, 10]
  
# Initializing k
k = 6
  
# Printing original list 
print ("The original list is : " + str(test_list))
  
# Using naive method 
# to find smallest number
# greater than K
min_val = 10000000
for i in test_list :
    if min_val > i and i > k :
        min_val = i
  
# Printing result 
print ("The minimum value greater than 6 is : " + str(min_val))

Output :

The original list is : [1, 4, 7, 5, 10]
The minimum value greater than 6 is : 7

Method #2 : Using min() + generator expression
min() returns the minimum number in a sequence and coupling it with a generator expression can perform this task in much concise way and hence more useful when required to save time.

# Python3 code to demonstrate 
# smallest number greater than K
# using min() + generator expression
  
# Initializing list 
test_list = [1, 4, 7, 5, 10]
  
# Initializing k
k = 6
  
# Printing original list 
print ("The original list is : " + str(test_list))
  
# Using min() + generator expression
# to find smallest number
# greater than K
min_val = min(i for i in test_list if i > k)
  
# Printing result 
print ("The minimum value greater than 6 is : " + str(min_val))

Output :

The original list is : [1, 4, 7, 5, 10]
The minimum value greater than 6 is : 7

Method #3 : min() + filter()
Similar approach to method above, just to filter the numbers in list greater than k, filter() instead of generator expression is used in this approach. Works in a similar way as above.

# Python3 code to demonstrate 
# smallest number greater than K
# using min() + filter()
  
# Initializing list 
test_list = [1, 4, 7, 5, 10]
  
# Initializing k
k = 6
  
# Printing original list 
print ("The original list is : " + str(test_list))
  
# Using min() + filter()
# to find smallest number
# greater than K
min_val = min(filter(lambda i: i > k, test_list))
  
# Printing result 
print ("The minimum value greater than 6 is : " + str(min_val))

Output :

The original list is : [1, 4, 7, 5, 10]
The minimum value greater than 6 is : 7

Method #4 : Using sort() + bisect_right()
bisect_right() coupled with sort() performs the task of binary search for us, and hence is a good option to achieve the solution to this problem. bisect_right() because it returns strictly greater number, not the number itself if it is present in the list.

# Python3 code to demonstrate 
# smallest number greater than K
# using sort() + bisect_right()
from bisect import bisect_right
  
# Initializing list 
test_list = [1, 4, 7, 5, 10]
  
# Initializing k
k = 6
  
# Printing original list 
print ("The original list is : " + str(test_list))
  
# Using sort() + bisect_right()
# to find smallest number
# greater than K
test_list.sort()
min_val = test_list[bisect_right(test_list, k)]
  
# Printing result 
print ("The minimum value greater than 6 is : " + str(min_val))

Output :

The original list is : [1, 4, 7, 5, 10]
The minimum value greater than 6 is : 7

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