diff --git a/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/README.md b/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/README.md
index a831982b8ccd9..681e8876240f2 100644
--- a/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/README.md	
+++ b/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/README.md	
@@ -207,6 +207,24 @@ impl Solution {
 }
 ```
 
+#### C#
+
+```cs
+public class Solution {
+    public int CountPermutations(int[] complexity) {
+        const int mod = (int) 1e9 + 7;
+        long ans = 1;
+        for (int i = 1; i < complexity.Length; ++i) {
+            if (complexity[i] <= complexity[0]) {
+                return 0;
+            }
+            ans = ans * i % mod;
+        }
+        return (int) ans;
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->
diff --git a/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/README_EN.md b/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/README_EN.md
index ef76ed93f5892..c46c22e1d01d8 100644
--- a/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/README_EN.md	
+++ b/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/README_EN.md	
@@ -203,6 +203,24 @@ impl Solution {
 }
 ```
 
+#### C#
+
+```cs
+public class Solution {
+    public int CountPermutations(int[] complexity) {
+        const int mod = (int) 1e9 + 7;
+        long ans = 1;
+        for (int i = 1; i < complexity.Length; ++i) {
+            if (complexity[i] <= complexity[0]) {
+                return 0;
+            }
+            ans = ans * i % mod;
+        }
+        return (int) ans;
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->
diff --git a/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/Solution.cs b/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/Solution.cs
new file mode 100644
index 0000000000000..c7a066af48bd9
--- /dev/null
+++ b/solution/3500-3599/3577.Count the Number of Computer Unlocking Permutations/Solution.cs	
@@ -0,0 +1,13 @@
+public class Solution {
+    public int CountPermutations(int[] complexity) {
+        const int mod = (int) 1e9 + 7;
+        long ans = 1;
+        for (int i = 1; i < complexity.Length; ++i) {
+            if (complexity[i] <= complexity[0]) {
+                return 0;
+            }
+            ans = ans * i % mod;
+        }
+        return (int) ans;
+    }
+}