When offering an ordering of a list, there are two ways to interpret it: 1. This ordering supplies the location to which each item should be moved. 2. This ordering supplies the location from which each item should be pulled. So, for instance, if the original list is [a, b, c] and the ordering you wish to apply is [2, 3, 1], by method (1) you ge…

gistfile1.sage

ln = 9

yesses = 0
nos = 0
for p in permutations(range(ln)):
    ys = [0] * ln
    for i in range(ln):
        ys[p[i]] = i
    if ys == p:
        yesses += 1
    else:
        nos += 1
print yesses / (yesses + nos)