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diff --git a/src/util/longest-common-suffix.h b/src/util/longest-common-suffix.h
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Inkscape::Algorithms::nearest_common_ancestor
+ *
+ * Authors:
+ *   MenTaLguY <mental@rydia.net>
+ *
+ * Copyright (C) 2004 MenTaLguY
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifndef SEEN_INKSCAPE_ALGORITHMS_NEAREST_COMMON_ANCESTOR_H
+#define SEEN_INKSCAPE_ALGORITHMS_NEAREST_COMMON_ANCESTOR_H
+
+#include <iterator>
+#include <functional>
+
+namespace Inkscape {
+
+namespace Algorithms {
+
+/**
+ * Time costs:
+ *
+ * The case of sharing a common successor is handled in O(1) time.
+ *
+ * If \a a is the nearest common ancestor, then runs in O(len(rest of b)) time.
+ *
+ * Otherwise, runs in O(len(a) + len(b)) time.
+ */
+
+template <typename ForwardIterator>
+ForwardIterator nearest_common_ancestor(ForwardIterator a, ForwardIterator b, ForwardIterator end)
+{
+    if ( a == end || b == end ) {
+        return end;
+    }
+
+    /* Handle in O(1) time the common cases of identical lists or tails. */
+    {
+        /* identical lists? */
+        if ( a == b ) {
+            return a;
+        }
+
+        /* identical tails? */
+        ForwardIterator tail_a(a);
+        ForwardIterator tail_b(b);
+        if ( ++tail_a == ++tail_b ) {
+            return tail_a;
+        }
+    }
+
+    /* Build parallel lists of suffixes, ordered by increasing length. */
+
+    ForwardIterator lists[2] = { a, b };
+    std::vector<ForwardIterator> suffixes[2];
+
+    for ( int i=0 ; i < 2 ; i++ ) {
+        for ( ForwardIterator iter(lists[i]) ; iter != end ; ++iter ) {
+            if ( iter == lists[1-i] ) {
+                // the other list is a suffix of this one
+                return lists[1-i];
+            }
+            suffixes[i].push_back(iter);
+        }
+    }
+
+    /* Iterate in parallel through the lists of suffix lists from shortest to
+     * longest, stopping before the first pair of suffixes that differs
+     */
+
+    ForwardIterator longest_common(end);
+
+    while ( !suffixes[0].empty() && !suffixes[1].empty() &&
+             suffixes[0].back() == suffixes[1].back() )
+    {
+        longest_common = suffixes[0].back();
+        suffixes[0].pop_back();
+        suffixes[1].pop_back();
+    }
+
+    return longest_common;
+}
+
+}
+
+}
+
+#endif /* !SEEN_INKSCAPE_ALGORITHMS_NEAREST_COMMON_ANCESTOR_H */
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :