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class NqueenJavaSeq {
static int repeat = 10;
static int size = 14;
static int cutOff = 7;
static class Board {
int queens, limit, left, down, right, kill;
}
static Board init(int width) {
Board b = new Board();
b.queens = width;
b.limit = 1 << width;
b.left = 0;
b.down = 0;
b.right = 0;
b.kill = 0;
return b;
}
static Board put(Board b, int bit) {
Board r = new Board();
r.queens = b.queens - 1;
r.limit = b.limit;
r.left = (b.left | bit) >> 1;
r.down = b.down | bit;
r.right = (b.right | bit) << 1;
r.kill = r.left | r.down | r.right;
return r;
}
static int ssum(Board board, int bit) {
int sum = 0;
while (bit < board.limit) {
if ((board.kill & bit) == 0)
sum += solve(put(board, bit));
bit <<= 1;
}
return sum;
}
static int psum(Board board, int bit) {
while (bit < board.limit) {
if ((board.kill & bit) == 0) {
int t = solve(put(board, bit));
int n = psum(board, bit << 1);
return n + t;
}
bit <<= 1;
}
return 0;
}
static int solve(Board board) {
if (board.queens == 0) {
return 1;
} else if (board.queens <= cutOff) {
return ssum(board, 1);
} else {
return psum(board, 1);
}
}
static int doit() {
return solve(init(size));
}
static void rep() {
for (int i = 0; i < repeat; i++) {
long t1 = System.currentTimeMillis();
int r = doit();
long t2 = System.currentTimeMillis();
System.out.println(" - {result: " + r + ", time: "
+ (double)(t2 - t1) / 1000.0 + "}");
}
}
public static void main(String[] args) {
if (args.length > 0) repeat = Integer.parseInt(args[0]);
if (args.length > 1) size = Integer.parseInt(args[1]);
if (args.length > 2) cutOff = Integer.parseInt(args[2]);
System.out.println(" bench: nqueen_java_seq");
System.out.println(" size: " + size);
System.out.println(" cutoff: " + cutOff);
System.out.println(" results:");
rep();
}
}
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