You cannot do this inplace: 

for( j = i+1; j < M; ++j ) idx[ i ] += N - idx[ M - j + i ];

[download]

as you are overwriting values that are still needed. This corresponds to the "reversing" the string part of the regex. In addition, you misread the formula, there is no += involved.

In reply to Re^9: Odometer pattern iterator (in C). by hdb
in thread Odometer pattern iterator (in C). (Updated.) by BrowserUk

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