diff --git a/Source/ac-library-csharp/String/StringLib.cs b/Source/ac-library-csharp/String/StringLib.cs
index 853af7f..20df0c6 100644
--- 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
index bf30736..1692172 100644
--- 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()
         {