Python Exercises: Two strings contain three letters at the same index

Last update on April 19 2025 13:04:53 (UTC/GMT +8 hours)

Count matches of three letters at same index.

Write a Python program that takes two strings. Count the number of times each string contains the same three letters at the same index.

Sample Data:
(“Red RedGreen”) -> 1
(“Red White Red White) -> 7
(“Red White White Red”) -> 0

Sample Solution-1:

Python Code:

# Define a function to check if two strings contain the same three letters at the same index
def test(text1, text2):
    # Initialize a counter variable to count the occurrences
    ctr = 0
    
    # Iterate through the range of indices up to the third-to-last index
    for i in range(len(text1) - 2):
        # Check if the substring of length 3 from both strings at the current index is the same
        if text1[i:i+3] == text2[i:i+3]:
            # If true, increment the counter
            ctr += 1
    
    # Return the count of occurrences
    return ctr

# Initialize two strings
text1 = "Red"
text2 = "RedGreen"

# Print the original strings
print("Original strings:", text1, text2)

# Print a message indicating the check for the same three letters at the same index
print("Check said two strings contain three letters at the same index:")

# Call the function to check and print the result
print(test(text1, text2))

# Repeat the process with different strings
text1 = "Red White"
text2 = "Red White"

# Print the original strings
print("\nOriginal strings:", text1, text2)

# Print a message indicating the check for the same three letters at the same index
print("Check said two strings contain three letters at the same index:")

# Call the function to check and print the result
print(test(text1, text2))

# Repeat the process with another set of different strings
text1 = "Red White"
text2 = "White Red"

# Print the original strings
print("\nOriginal strings:", text1, text2)

# Print a message indicating the check for the same three letters at the same index
print("Check said two strings contain three letters at the same index:")

# Call the function to check and print the result
print(test(text1, text2))

Sample Output:

Original strings: Red RedGreen
Check said two strings contain three letters at the same index:
1
Original strings: Red White Red White
Check said two strings contain three letters at the same index:
7
Original strings: Red White White Red
Check said two strings contain three letters at the same index:
0

Flowchart:

Sample Solution-2:

Python Code:

# Define a function to count the occurrences of three consecutive letters at the same index in two strings
def test(text1, text2):
    # Use a list comprehension to create a list of 1s for each match, then sum the list to get the count
    return sum([1 for i in range(len(text1)-2) if text1[i:i+3] == text2[i:i+3]])

# Initialize two strings
text1 = "Red"
text2 = "RedGreen"

# Print the original strings
print("Original strings:", text1, text2)

# Print a message indicating the check for the same three letters at the same index
print("Check said two strings contain three letters at the same index:")

# Call the function to check and print the result
print(test(text1, text2))

# Repeat the process with different strings
text1 = "Red White"
text2 = "Red White"

# Print the original strings
print("\nOriginal strings:", text1, text2)

# Print a message indicating the check for the same three letters at the same index
print("Check said two strings contain three letters at the same index:")

# Call the function to check and print the result
print(test(text1, text2))

# Repeat the process with another set of different strings
text1 = "Red White"
text2 = "White Red"

# Print the original strings
print("\nOriginal strings:", text1, text2)

# Print a message indicating the check for the same three letters at the same index
print("Check said two strings contain three letters at the same index:")

# Call the function to check and print the result
print(test(text1, text2))

Sample Output:

Original strings: Red RedGreen
Check said two strings contain three letters at the same index:
1
Original strings: Red White Red White
Check said two strings contain three letters at the same index:
7
Original strings: Red White White Red
Check said two strings contain three letters at the same index:
0

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program that takes two strings and counts the number of positions where both strings have the same three-letter sequence.
Write a Python program to slide a window of three characters over two strings and count matching triplets at the same indices.
Write a Python program to implement a function that returns the count of matching three-letter segments from two equal-length strings.
Write a Python program to use list comprehension and slicing to compare triplets from two strings and tally the matches.

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