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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libgomp/testsuite/libgomp.c/nqueens-1.c | |
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Diffstat (limited to 'libgomp/testsuite/libgomp.c/nqueens-1.c')
-rw-r--r-- | libgomp/testsuite/libgomp.c/nqueens-1.c | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/libgomp/testsuite/libgomp.c/nqueens-1.c b/libgomp/testsuite/libgomp.c/nqueens-1.c new file mode 100644 index 000000000..1fdc67b29 --- /dev/null +++ b/libgomp/testsuite/libgomp.c/nqueens-1.c @@ -0,0 +1,66 @@ +/* { dg-do run } */ +/* { dg-options "-O2 -fopenmp" } */ +/* { dg-require-effective-target tls_runtime } */ + +#include <omp.h> +#include <stdio.h> +#include <string.h> + +int cnt; +#pragma omp threadprivate (cnt) + +void +nqueens (char *a, int n, int pos) +{ + /* b[i] = j means the queen in i-th row is in column j. */ + char b[pos + 1]; + int i, j; + memcpy (b, a, pos); + for (i = 0; i < n; i++) + { + for (j = 0; j < pos; j++) + if (b[j] == i || b[j] == i + pos - j || i == b[j] + pos - j) + break; + if (j < pos) + continue; + if (pos == n - 1) + /* Found a solution. Could output it here. */ + ++cnt; + else + { + b[pos] = i; + #pragma omp task + nqueens (b, n, pos + 1); + } + } +} + +int +main (int argc, char **argv) +{ + int n = 8; + if (argc >= 2) + n = strtoul (argv[1], NULL, 0); + if (n < 1 || n > 127) + { + fprintf (stderr, "invalid count %d\n", n); + return 1; + } + cnt = 0; + double stime = omp_get_wtime (); + nqueens ("", n, 0); + printf ("serial N %d solutions # %d time %f\n", n, cnt, omp_get_wtime () - stime); + #pragma omp parallel + cnt = 0; + stime = omp_get_wtime (); + int tempcnt = 0; + #pragma omp parallel reduction (+:tempcnt) + { + #pragma omp single + nqueens ("", n, 0); + tempcnt = cnt; + } + cnt = tempcnt; + printf ("parallel N %d solutions # %d time %f\n", n, cnt, omp_get_wtime () - stime); + return 0; +} |