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rotating-list-t-in-dart.dart
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rotating-list-t-in-dart.dart
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// Want to support my work 🤝? https://buymeacoffee.com/vandad
extension Rotate<T> on List<T> {
int _rotationTimes(int places) {
if (isEmpty) {
return 0;
}
if (places == 0) {
throw ArgumentError('places should be more than 0');
}
return places % length;
}
List<T> rotatedRight(int places) {
final times = _rotationTimes(places);
if (times == 0) {
return this;
} else {
final cutOff = length - times;
return sublist(cutOff)..addAll(sublist(0, cutOff));
}
}
List<T> rotatedLeft(int places) {
final times = _rotationTimes(places);
if (times == 0) {
return this;
} else {
return sublist(times)..addAll(sublist(0, times));
}
}
}
extension Equality<T extends Comparable> on List<T> {
bool isEqualTo(List<T> other) {
if (other.length != length) {
return false;
}
for (var i = 0; i < length; i++) {
if (other[i] != this[i]) {
return false;
}
}
return true;
}
}
const arr = [1, 2, 3];
void testIt() {
assert(arr.rotatedRight(1).isEqualTo([3, 1, 2]));
assert(arr.rotatedRight(2).isEqualTo([2, 3, 1]));
assert(arr.rotatedRight(3).isEqualTo([1, 2, 3]));
assert(arr.rotatedRight(4).isEqualTo([3, 1, 2]));
assert(arr.rotatedLeft(1).isEqualTo([2, 3, 1]));
assert(arr.rotatedLeft(2).isEqualTo([3, 1, 2]));
assert(arr.rotatedLeft(3).isEqualTo([1, 2, 3]));
assert(arr.rotatedLeft(4).isEqualTo([2, 3, 1]));
}