diff --git a/solution/621/main.go b/solution/621/main.go
new file mode 100644
index 0000000..c9ae1da
--- /dev/null
+++ b/solution/621/main.go
@@ -0,0 +1,29 @@
+package main
+
+func leastInterval(tasks []byte, n int) int {
+	if n == 0 {
+		return len(tasks)
+	}
+
+	cnt := make([]int, 26)
+	for _, task := range tasks {
+		cnt[task - 'A']++
+	}
+
+	var maxCount, sameMaxCount int
+	for _, c := range cnt {
+		if c > maxCount {
+			maxCount = c
+			sameMaxCount = 1
+		} else if c == maxCount {
+			sameMaxCount++
+		}
+	}
+
+	res := (n + 1) * (maxCount - 1) + sameMaxCount
+    if (res > len(tasks)) {
+        return res
+    } else {
+        return len(tasks)
+    }
+}