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February 24, 2017 21:46
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Doomsday Fuel | |
============= | |
Making fuel for the LAMBCHOP's reactor core is a tricky process because of the exotic matter involved. It starts as raw ore, then | |
during processing, begins randomly changing between forms, eventually reaching a stable form. There may be multiple stable forms that a | |
sample could ultimately reach, not all of which are useful as fuel. | |
Commander Lambda has tasked you to help the scientists increase fuel creation efficiency by predicting the end state of a given ore | |
sample. You have carefully studied the different structures that the ore can take and which transitions it undergoes. It appears that, | |
while random, the probability of each structure transforming is fixed. That is, each time the ore is in 1 state, it has the same | |
probabilities of entering the next state (which might be the same state). You have recorded the observed transitions in a matrix. The | |
others in the lab have hypothesized more exotic forms that the ore can become, but you haven't seen all of them. | |
Write a function answer(m) that takes an array of array of nonnegative ints representing how many times that state has gone to the next | |
state and return an array of ints for each terminal state giving the exact probabilities of each terminal state, represented as the | |
numerator for each state, then the denominator for all of them at the end and in simplest form. The matrix is at most 10 by 10. It is | |
guaranteed that no matter which state the ore is in, there is a path from that state to a terminal state. That is, the processing will | |
always eventually end in a stable state. The ore starts in state 0. The denominator will fit within a signed 32-bit integer during the | |
calculation, as long as the fraction is simplified regularly. | |
For example, consider the matrix m: | |
[ | |
[0,1,0,0,0,1], # s0, the initial state, goes to s1 and s5 with equal probability | |
[4,0,0,3,2,0], # s1 can become s0, s3, or s4, but with different probabilities | |
[0,0,0,0,0,0], # s2 is terminal, and unreachable (never observed in practice) | |
[0,0,0,0,0,0], # s3 is terminal | |
[0,0,0,0,0,0], # s4 is terminal | |
[0,0,0,0,0,0], # s5 is terminal | |
] | |
So, we can consider different paths to terminal states, such as: | |
s0 -> s1 -> s3 | |
s0 -> s1 -> s0 -> s1 -> s0 -> s1 -> s4 |
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