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/*
** Determine the permutation index for a given permutation list.
** Written by Thad Smith III, Boulder, CO 8/31/91
** Hereby contributed to the Public Domain.
**
** The following function computes the ordinal of the given permutation,
** which is index of the permutation in sorting order:
** 1, 2, ..., n-1, n is index 0
** 1, 2, ..., n, n-1 is index 1
** ...
** n, n-1, ..., 2, 1 is index n! -1
**
** The actual values of the elements are immaterial, only the relative
** ordering of the values is used.
**
** pit[] is the array of elements of length size.
** The return value is the permutation index.
*/
int perm_index (char pit[], int size)
{
int i;
register int j, ball;
int index = 0;
for (i = 1; i < size; i++)
{
ball = pit[i-1];
for (j = i; j < size; j++)
{
if (ball > pit[j])
index ++;
}
index *= size - i;
}
return index;
}
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