73 lines
2.3 KiB
C++
73 lines
2.3 KiB
C++
// RUN: %clang_cc1 -std=c++11 -fsyntax-only %s
|
|
|
|
typedef unsigned long uint64_t;
|
|
|
|
struct Board {
|
|
uint64_t State;
|
|
bool Failed;
|
|
|
|
constexpr Board() : State(0), Failed(false) {}
|
|
constexpr Board(const Board &O) : State(O.State), Failed(O.Failed) {}
|
|
constexpr Board(uint64_t State, bool Failed = false) :
|
|
State(State), Failed(Failed) {}
|
|
constexpr Board addQueen(int Row, int Col) {
|
|
return Board(State | ((uint64_t)Row << (Col * 4)));
|
|
}
|
|
constexpr int getQueenRow(int Col) {
|
|
return (State >> (Col * 4)) & 0xf;
|
|
}
|
|
constexpr bool ok(int Row, int Col) {
|
|
return okRecurse(Row, Col, 0);
|
|
}
|
|
constexpr bool okRecurse(int Row, int Col, int CheckCol) {
|
|
return Col == CheckCol ? true :
|
|
getQueenRow(CheckCol) == Row ? false :
|
|
getQueenRow(CheckCol) == Row + (Col - CheckCol) ? false :
|
|
getQueenRow(CheckCol) == Row + (CheckCol - Col) ? false :
|
|
okRecurse(Row, Col, CheckCol + 1);
|
|
}
|
|
constexpr bool at(int Row, int Col) {
|
|
return getQueenRow(Col) == Row;
|
|
}
|
|
constexpr bool check(const char *, int=0, int=0);
|
|
};
|
|
|
|
constexpr Board buildBoardRecurse(int N, int Col, const Board &B);
|
|
constexpr Board buildBoardScan(int N, int Col, int Row, const Board &B);
|
|
constexpr Board tryBoard(const Board &Try,
|
|
int N, int Col, int Row, const Board &B) {
|
|
return Try.Failed ? buildBoardScan(N, Col, Row, B) : Try;
|
|
}
|
|
constexpr Board buildBoardScan(int N, int Col, int Row, const Board &B) {
|
|
return Row == N ? Board(0, true) :
|
|
B.ok(Row, Col) ?
|
|
tryBoard(buildBoardRecurse(N, Col + 1, B.addQueen(Row, Col)),
|
|
N, Col, Row+1, B) :
|
|
buildBoardScan(N, Col, Row + 1, B);
|
|
}
|
|
constexpr Board buildBoardRecurse(int N, int Col, const Board &B) {
|
|
return Col == N ? B : buildBoardScan(N, Col, 0, B);
|
|
}
|
|
constexpr Board buildBoard(int N) {
|
|
return buildBoardRecurse(N, 0, Board());
|
|
}
|
|
|
|
constexpr Board q8 = buildBoard(8);
|
|
|
|
constexpr bool Board::check(const char *p, int Row, int Col) {
|
|
return
|
|
*p == '\n' ? check(p+1, Row+1, 0) :
|
|
*p == 'o' ? at(Row, Col) && check(p+1, Row, Col+1) :
|
|
*p == '-' ? !at(Row, Col) && check(p+1, Row, Col+1) :
|
|
*p == 0 ? true :
|
|
false;
|
|
}
|
|
static_assert(q8.check(
|
|
"o-------\n"
|
|
"------o-\n"
|
|
"----o---\n"
|
|
"-------o\n"
|
|
"-o------\n"
|
|
"---o----\n"
|
|
"-----o--\n"
|
|
"--o-----\n"), "");
|