Trivial Description
The Fisher-Yates algorithm in the PermutationSampler has a conditional if statement within the loop that checks if the step is the first in the loop. It then swaps a position with itself. For example for the towards head variant:
for (int i = 0; i <= start; i++) { final int target; // Check for start if (i == start) { target = start; // this means target == i } else { target = rng.nextInt(start - i + 1) + i; } // if target == i then this step is not needed. final int temp = list[target]; list[target] = list[i]; list[i] = temp; }
This can be removed by altering the iteration loop:
for (int i = start; i > 0; i--) { final int target = rng.nextInt(i + 1); final int temp = list[target]; list[target] = list[i]; list[i] = temp; }
An equivalent fix is available for the shuffle towards the tail.
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