1307. verbal arithmetic puzzle

Given an equation, represented by words on the left side and the result on the right side.

You need to check if the equation is solvable under the following rules:

• Each character is decoded as one digit (0 - 9).
• No two characters can map to the same digit.
• Each words[i] and result are decoded as one number without leading zeros.
• Sum of numbers on the left side (words) will equal to the number on the right side (result).

Return true if the equation is solvable, otherwise return false.

references

• https://leetcode.com/problems/verbal-arithmetic-puzzle/solutions/463921/python-backtracking-with-pruning-tricks