ExpNo 8 : Solve Cryptarithmetic Problem,a CSP(Constraint Satisfaction Problem) using Python

Name: K Nishal

Register Number: 2305001021

Aim:

To solve Cryptarithmetic Problem,a CSP(Constraint Satisfaction Problem) using Python

Procedure:

Step 1: Start the program.

Step 2: Read three input words from the user —WORD1, WORD2, and RESULT.

Step 3: Combine all letters from the three words and find the unique letters.

a)If there are more than 10 unique letters → stop (since digits 0–9 can only represent 10 unique letters).

Step 4: Generate all possible digit assignments (permutations) for these unique letters.

Step 5: For each permutation:

  a) Create a mapping of each letter to a digit.

  b) Check if any leading letter of the three words is assigned 0 — if yes, skip this permutation.

  c) Convert each word into its numeric equivalent using the current mapping.

  d) Check if WORD1 + WORD2 == RESULT.

Step 6: If a valid mapping is found that satisfies the equation:

  a) Display the numeric values of WORD1, WORD2, and RESULT.

  b) Display the letter-to-digit mapping.

Step 7: If no valid mapping is found after checking all permutations, print “No solution found.”

Step 8: End the program.

PROGRAM

from itertools import permutations

def solve_cryptarithmetic(word1, word2, result):
 
    letters = set(word1 + word2 + result)
    if len(letters) > 10:
        print("Too many unique letters (max 10 allowed).")
        return None

    letters = list(letters)

    for perm in permutations(range(10), len(letters)):
        mapping = dict(zip(letters, perm))

        if mapping[word1[0]] == 0 or mapping[word2[0]] == 0 or mapping[result[0]] == 0:
            continue

        num1 = int("".join(str(mapping[ch]) for ch in word1))
        num2 = int("".join(str(mapping[ch]) for ch in word2))
        num_result = int("".join(str(mapping[ch]) for ch in result))

        if num1 + num2 == num_result:
            return num1, num2, num_result, mapping

    return None

word1 = input("Enter first word: ").upper()
word2 = input("Enter second word: ").upper()
result = input("Enter result word: ").upper()

solution = solve_cryptarithmetic(word1, word2, result)

if solution:
    num1, num2, num_result, mapping = solution
    print(f"\nSolution found!")
    print(f"{word1} = {num1}")
    print(f"{word2} = {num2}")
    print(f"{result} = {num_result}")
    print(f"Mapping: {mapping}")
else:
    print("No solution found.")

Output

---

Result:

Thus a Cryptarithmetic Problem was solved using Python successfully