We are stacking blocks to form a pyramid. Each block has a color which is a one letter string.
We are allowed to place any color block C on top of two adjacent blocks of colors A and B, if and only if ABC is an allowed triple.
We start with a bottom row of bottom, represented as a single string. We also start with a list of allowed triples allowed. Each allowed triple is represented as a string of length 3.
Return true if we can build the pyramid all the way to the top, otherwise false.
Example 1:
Input: bottom = "BCD", allowed = ["BCG", "CDE", "GEA", "FFF"]
Output: true
Explanation:
We can stack the pyramid like this:
A
/ \
G E
/ \ / \
B C D
We are allowed to place G on top of B and C because BCG is an allowed triple. Similarly, we can place E on top of C and D, then A on top of G and E.
Example 2:
Input: bottom = "AABA", allowed = ["AAA", "AAB", "ABA", "ABB", "BAC"] Output: false Explanation: We can't stack the pyramid to the top. Note that there could be allowed triples (A, B, C) and (A, B, D) with C != D.
Note:
<li><code>bottom</code> will be a string with length in range <code>[2, 8]</code>.</li>
<li><code>allowed</code> will have length in range <code>[0, 200]</code>.</li>
<li>Letters in all strings will be chosen from the set <code>{'A', 'B', 'C', 'D', 'E', 'F', 'G'}</code>.</li>