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authorcraig <craig@11d20701-8431-0410-a711-e3c959e3b870>2012-01-01 11:40:09 +0000
committercraig <craig@11d20701-8431-0410-a711-e3c959e3b870>2012-01-01 11:40:09 +0000
commit7ed83b6c6666eb8b6b104c211ae7e52907350372 (patch)
tree4430b556abac0ad660a0aacf1887d77f85d8be02 /scribus/plugins/tools/2geomtools/lib2geom/choose.h
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Branch 1.3.5 tree to 1.4.x tree, goodbye 1.3.x
git-svn-id: svn://scribus.net/branches/Version14x/Scribus@17163 11d20701-8431-0410-a711-e3c959e3b870
Diffstat (limited to 'scribus/plugins/tools/2geomtools/lib2geom/choose.h')
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1 files changed, 67 insertions, 0 deletions
diff --git a/scribus/plugins/tools/2geomtools/lib2geom/choose.h b/scribus/plugins/tools/2geomtools/lib2geom/choose.h
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+/*
+ * choose.h
+ *
+ * Copyright 2006 Nathan Hurst <njh@mail.csse.monash.edu.au>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ */
+
+#ifndef _CHOOSE_H
+#define _CHOOSE_H
+
+// XXX: Can we keep only the left terms easily?
+// this would more than halve the array
+// row index becomes n2 = n/2, row2 = n2*(n2+1)/2, row = row2*2+(n&1)?n2:0
+// we could also leave off the ones
+
+template <typename T>
+T choose(unsigned n, unsigned k) {
+ static std::vector<T> pascals_triangle;
+ static unsigned rows_done = 0;
+ // indexing is (0,0,), (1,0), (1,1), (2, 0)...
+ // to get (i, j) i*(i+1)/2 + j
+ if(k < 0 || k > n) return 0;
+ if(rows_done <= n) {// we haven't got there yet
+ if(rows_done == 0) {
+ pascals_triangle.push_back(1);
+ rows_done = 1;
+ }
+ while(rows_done <= n) {
+ unsigned p = pascals_triangle.size() - rows_done;
+ pascals_triangle.push_back(1);
+ for(unsigned i = 0; i < rows_done-1; i++) {
+ pascals_triangle.push_back(pascals_triangle[p]
+ + pascals_triangle[p+1]);
+ p++;
+ }
+ pascals_triangle.push_back(1);
+ rows_done ++;
+ }
+ }
+ unsigned row = (n*(n+1))/2;
+ return pascals_triangle[row+k];
+}
+
+#endif