Python program to find the character position of Kth word from a list of strings

Given a list of strings. The task is to find the index of the character position for the word, which lies at the Kth index in the list of strings.

Examples:

Input : test_list = [“geekforgeeks”, “is”, “best”, “for”, “geeks”], K = 21 
Output : 0
Explanation : 21st index occurs in “geeks” and point to “g” which is 0th element of word.

Input : test_list = [“geekforgeeks”, “is”, “best”, “for”, “geeks”], K = 15 
Output : 1
Explanation : 15th index occurs in “best” and point to “e” which is 1st element of word.

Method #1 : Using enumerate() + list comprehension

In this, we use nested enumerate() to check indices for words, and strings in the list, list comprehension is used to encapsulate logic in 1 liner.

Python3

# Python3 code to demonstrate working of
# Word Index for K position in Strings List
# Using enumerate() + list comprehension

# initializing list
test_list = ["geekforgeeks", "is", "best", "for", "geeks"]

# printing original list
print("The original list is : " + str(test_list))

# initializing K
K = 20

# enumerate to get indices of all inner and outer list
res = [ele[0] for sub in enumerate(test_list) for ele in enumerate(sub[1])]

# getting index of word
res = res[K]

# printing result
print("Index of character at Kth position word : " + str(res))

Output

The original list is : ['geekforgeeks', 'is', 'best', 'for', 'geeks']
Index of character at Kth position word : 2

Time Complexity: O(n²)
Auxiliary Space: O(n)

Method #2 : Using next() + zip() + count()

In this, we pair up the number of words with their counts using zip(), and accumulate till we don’t reach Kth Index.

Python3

# Python3 code to demonstrate working of
# Word Index for K position in Strings List
# Using next() + zip() + count()

from itertools import count

# initializing list
test_list = ["geekforgeeks", "is", "best", "for", "geeks"]

# printing original list
print("The original list is : " + str(test_list))

# initializing K
K = 20

# count() for getting count
# pairing using zip()
cnt = count()
res = next(j for sub in test_list for j, idx in zip(
    range(len(sub)), cnt) if idx == K)

# printing result
print("Index of character at Kth position word : " + str(res))

Output

The original list is : ['geekforgeeks', 'is', 'best', 'for', 'geeks']
Index of character at Kth position word : 2

Time Complexity: O(n²)
Auxiliary Space: O(n)

Method 3:  Using nested loop

Python3

# Python3 code to demonstrate working of
# Word Index for K position in Strings List
# Using nested loop

# initializing list
test_list = ["geekforgeeks", "is", "best", "for", "geeks"]

# printing original list
print("The original list is : " + str(test_list))

# initializing K
K = 20

# initializing index counter
idx = 0

# iterating over each word in the list
for word in test_list:

    # if the kth position is in the current word
    if idx + len(word) > K:

        # printing result
        print("Index of character at Kth position word : " + str(K - idx))
        break

    # if the kth position is not in the current word
    else:
        idx += len(word)

# if the kth position is beyond the end of the list
else:
    print("K is beyond the end of the list")

Output

The original list is : ['geekforgeeks', 'is', 'best', 'for', 'geeks']
Index of character at Kth position word : 2