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    <p>So you only need to print the length of the list, not the list itself? That helps, because it simplifies memory management (which is an issue for c).</p> <p>This is really just a glorified search. At each point you need to know (1) the current value (if any); (2) the current length (if any); (3) the position in the list; (4) the largest length known. Using a length of zero helps track when you have no current value (so you don't need a "magic" initial value). The return value should be the largest length.</p> <p>On each recursion you can either skip the current number or include it in the list (but only if it is less than the current value).</p> <p>so the code is just:</p> <pre> <code>#include &lt;stdio.h&gt; int max(int a, int b) { return a > b ? a : b; } int find(int* data, int total_length, int offset, int previous, int run_length, int max_length) { // update max length if it has improved if (run_length &gt; max_length) max_length = run_length; // if we are at the end, return max if (offset == total_length) return max_length; // if the current value is too small, we cannot include it if (run_length && data[offset] &lt;= previous) return find(data, total_length, offset+1, previous, run_length, max_length); // otherwise, we want the best of either including it or not return max( // try including it find(data, total_length, offset+1, data[offset], run_length+1, max_length), // try excluding it find(data, total_length, offset+1, previous, run_length, max_length)); } // test int main(int argc, char *argv) { int data[] = { 88, 1, 22, 3, 34, 6, 54, 9, 19 }; printf("%d\n", find(data, 9, 0, 0, 0, 0)); return 0; } </code> </pre> <p>obviously this is terrible c code (not because I didn't use array initialization, which someone "kindly" fixed (although they didn't bother to vote this answer - I guess they think I am motivated to post here by learning from their deep knowledge of C syntax) but because it uses the call stack where it would be more efficient to use a separate memory structure).</p> <p>(also, I have to say, writing something like this is much easier as a recursive function than as doing it in a loop, because you just write down what you want to happen - if you had a loop then you would need to worry about changing values and resetting them and all that mess. The problem is that it abuses the stack horribly).</p>
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    1. PORecursive algorithm to select ascending noncontiguous numbers from a list
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    1. CO`return 0` from main() in C. You could use [`int data[] = {88, 1, 22, 3, 34, 6, 54, 9, 19};`](http://ideone.com/Y9ECC).
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    2. CODoes 'ascending' mean 'non-descending' or 'strictly ascending'? Your code implies that 'ascending' == 'strictly ascending'.
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    3. COfixed return value, thanks.
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