Re: SO rotate question

[simendsjo]

Pelle wrote:

On 09/02/2010 10:24 PM, bearophile wrote:

simendsjo:

Suggestions for D-ifying the code is welcome.

Your unit tests are not good enough, they miss some important corner cases.

This my first version in D2:

import std.string: indexOf;

/// return True if s1 is a rotated version of s2
bool isRotated(T)(T[] s1, T[] s2) {
     return (s1.length + s2.length == 0) ||
            (s1.length == s2.length&&  indexOf(s1 ~ s1, s2) != -1);
}

unittest { // of isRotated
     assert(isRotated("", ""));
     assert(!isRotated("", "x"));
     assert(!isRotated("x", ""));
     assert(isRotated("x", "x"));

     string s = "rotato";
     assert(isRotated(s, "rotato"));
     assert(isRotated(s, "otator"));
     assert(isRotated(s, "tatoro"));
     assert(isRotated(s, "atorot"));
     assert(isRotated(s, "torota"));
     assert(isRotated(s, "orotat"));

     assert(!isRotated(s, "rotator"));
     assert(!isRotated(s, "rotat"));
     assert(!isRotated(s, "rotata"));
}

void main() {}

Bye,
bearophile

This is what I wrote:

bool isRotated(T)(T[] a, T[] b) {

return a.length == b.length && (a.length == 0 || canFind(chain(a,a), b));

}

Use chain to avoid allocation.

canFind isn't really the best possible name, is it?

Sweet! Thats what I was looking for!