Building up a Word

You are given an input array of strings, ordered by ascending length.

Write a function that returns true if, for each pair of consecutive strings, the second string can be formed from the first by adding a single letter either at the beginning or end.

Examples

canBuild(["a", "at", "ate", "late", "plate", "plates"]) ➞ true

canBuild(["a", "at", "ate", "late", "plate", "plater", "platter"]) ➞ false
// "platter" is formed by adding "t" in the middle of "plater"

canBuild(["it", "bit", "bite", "biters"]) ➞ false
// "biters" is formed by adding two letters - we can only add one

canBuild(["mean", "meany"]) ➞ true

Notes

• Return false if a word is NOT formed by adding only one letter.
• Return false if the letter is added to the middle of the previous word.
• Letters in tests will all be lower case.