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Without //= patch:
@x=@_;my%c;$e=sub{my$v=pop;exists$c{$v}?$c{$v}:$c{$v}=$v<0?0:$v==0||gr
+ep&$e($v-$_),@x};$t=$s=0;{&$e(++$t)?$t-$s>=$x[0]&&last:($s=$t);redo}$
+s

With //= patch:
@x=@_;my%c;$e=sub{my$v=pop;$c{$v}//=$v<0?0:$v==0||grep&$e($v-$_),@x};$
+t=$s=0;{&$e(++$t)?$t-$s>=$x[0]&&last:($s=$t);redo}$s

@x=@_;my%c;$e=sub{my$v=pop;$c{$v}//=$v==0||$v>0&&grep&$e($v-$_),@x};$t
+=$s=0;{&$e(++$t)?$t-$s>=$x[0]&&last:($s=$t);redo}$s

@x=@_;my%c;$e=sub{my$v=pop;$c{$v}//=!$v||$v>0&&grep&$e($v-$_),@x};for(
+$t=$s=0;$t-$s<$x[0];&$e(++$t)or$s=$t){}$s