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// 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"), "");
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