arr[idx++] = i;
bingbangboom-lab
，更多细节参见同城约会
I learned that for 4-SAT, if clause to variable ratio is more than 10, the generated problems become difficult to solve, and the likelihood of formula to be SAT or UNSAT is close to 50%. So I generated 3 types of formulas:
“한국은 ‘얼죽아’의 본고장”… 스타벅스, 韓서 세계 최초 ‘에어로카노’ 출시