Merge pull request #96 from kzrnm/feature/sa

Add SuffixArray test
kzrnm · Jan 24, 2023 · 15ba366 · 15ba366
2 parents d162b45 + cdf8545
commit 15ba366
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Showing 2 changed files with 22 additions and 1 deletion.
diff --git a/Source/ac-library-csharp/String/StringLib.cs b/Source/ac-library-csharp/String/StringLib.cs
@@ -389,6 +389,7 @@ public static int[] SaIs(ReadOnlySpan<int> s, int upper, int thresholdNaive, int
                 Induce(lms, s, sa, ls, sumS, sumL);
 
                 // LMSを再帰的にソート
+                // m の値は再帰ごとに半分以下になるので再帰の回数も log(n) に抑えられる
                 if (m > 0)
                 {
                     var sortedLms = new SimpleList<int>(m);

diff --git a/Test/ac-library-csharp.Test/String/StringLibTest.cs b/Test/ac-library-csharp.Test/String/StringLibTest.cs
@@ -271,7 +271,7 @@ public void SAAllABTest()
             }
         }
         [Fact]
-        public void SA()
+        public void SuffixArray()
         {
             var s = "missisippi";
 
@@ -296,6 +296,26 @@ public void SA()
                 s[sa[i]..].Should().Be(answer[i]);
             }
         }
+        [Fact]
+        public void SuffixArrayInt()
+        {
+            int[] s, sa;
+            s = Enumerable.Range(0, 500000).SelectMany(i => new[] { i, ~i }).ToArray();
+            sa = StringLib.SuffixArray(s);
+            sa.Should().Equal(
+                Enumerable.Range(0, 500000).Select(i => 999999 - 2 * i).Concat(
+                    Enumerable.Range(0, 500000).Select(i => 2 * i))
+                );
+
+            s = Enumerable.Range(0, 1000000).ToArray();
+            sa = StringLib.SuffixArray(s);
+            sa.Should().Equal(s);
+
+            s = Enumerable.Range(0, 1000000).Reverse().ToArray();
+            sa = StringLib.SuffixArray(s);
+            sa.Should().Equal(s);
+        }
+
         [Fact]
         public void SASingle()
         {