Leetcode n-queens II Retrospective Search

For each case of N-queens, the number of permutations of n-queens for each case is answered.

L,r and C are the pieces of each type of lattice.

L judge that the diagonal lattice R is judging by the diagonal lattice C judging is such a vertical bar lattice

Enumerate each line to put a piece of chess, judging whether conflict with the previous, if not conflict always let answer +1

1 classSolution {2  Public:3std::vector<BOOL>l,r,c;4     intans;5     intTotalnqueens (intN) {6L.resize (2* n +1,false);7R.resize (2* n +1,false);8C.resize (N,false);9Ans =0;TenN_queens (0, n); One l.clear (); A r.clear (); - c.clear (); -         returnans; the     } -     voidN_queens (intNowintN) {//Calculate the possible number of N_queens -         if(now = =N) {//recursion to the end -ans++; +             return; -         } +         Else{ A              for(inti =0; I < n; ++i) { at                 if(Is_legal (now, I, N)) {//not in conflict with before put a pawn on it. -Init (now, I, N,true); -N_queens (now +1, n); -Init (now, I, N,false); -                 } -             } in         } -     } to     BOOLIs_legal (intXintYintN) {//Determine if conflict with previous +         return!c[y] &&!l[x-y + n] &&!r[x +y]; -     } the     voidInitintXintYintNBOOLb) {//l,r and C have a value of B *C[y] = l[x-y + N] = r[x + y] =b; $     }Panax Notoginseng};

Leetcode n-queens II Retrospective Search