Python: Get all possible two digit letter combinations from a digit string

Last update on April 17 2025 13:01:45 (UTC/GMT +8 hours)

Two-Digit Letter Combos

Write a Python program to get all possible two-digit letter combinations from a 1-9 digit string.

string_maps = {
"1": "abc",
"2": "def",
"3": "ghi",
"4": "jkl",
"5": "mno",
"6": "pqrs",
"7": "tuv",
"8": "wxy",
"9": "z"
}

Visual Presentation:

Python: Get all possible two digit letter combinations from a digit string

Sample Solution:

Python Code:

# Define a function 'letter_combinations' that generates letter combinations based on input digits.
def letter_combinations(digits):
    # Check if the input string is empty.
    if digits == "":
        return []
    
    # Define a mapping of digits to corresponding letters.
    string_maps = {
        "1": "abc",
        "2": "def",
        "3": "ghi",
        "4": "jkl",
        "5": "mno",
        "6": "pqrs",
        "7": "tuv",
        "8": "wxy",
        "9": "z"
    }
    
    # Initialize the result list with an empty string.
    result = [""]
    
    # Iterate through each digit in the input string.
    for num in digits:
        # Create a temporary list to store new combinations.
        temp = []
        
        # Iterate through each existing combination in the result list.
        for an in result:
            # Append each letter corresponding to the current digit to create new combinations.
            for char in string_maps[num]:
                temp.append(an + char)
        
        # Update the result list with the new combinations.
        result = temp
    
    # Return the final list of letter combinations.
    return result

# Define input digit strings and print the corresponding letter combinations.
digit_string = "47"
print(letter_combinations(digit_string))
digit_string = "29"
print(letter_combinations(digit_string))

Sample Output:

['jt', 'ju', 'jv', 'kt', 'ku', 'kv', 'lt', 'lu', 'lv']
['dz', 'ez', 'fz']

Explanation:

The above Python code defines a function called "letter_combinations()" that generates letter combinations based on input digits. Here's a brief explanation:

The function takes a string of digits ('digits') as input.
If the input string is empty, it returns an empty list.
It defines a mapping ('string_maps') of each digit to a string of corresponding letters.
It initializes a result list with an empty string.
It iterates through each digit in the input string.
For each existing combination in the result list, it appends each letter corresponding to the current digit to create new combinations.
It updates the result list with new combinations.
The function returns the final list of letter combinations.

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to generate all possible three-digit letter combinations from a digit string using a provided mapping.
Write a Python program to count the total number of possible letter combinations for a given digit string.
Write a Python program to generate all letter combinations from a digit string using both uppercase and lowercase mappings.
Write a Python program to produce letter combinations from a digit string and filter the results to only include valid dictionary words.

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Python Code Editor :

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