diff --git a/leetcode/0003.Longest-Substring-Without-Repeating-Characters/3. Longest Substring Without Repeating Characters.go b/leetcode/0003.Longest-Substring-Without-Repeating-Characters/3. Longest Substring Without Repeating Characters.go
index 90ee1e720..672dbdb54 100644
--- a/leetcode/0003.Longest-Substring-Without-Repeating-Characters/3. Longest Substring Without Repeating Characters.go	
+++ b/leetcode/0003.Longest-Substring-Without-Repeating-Characters/3. Longest Substring Without Repeating Characters.go	
@@ -5,20 +5,23 @@ func lengthOfLongestSubstring(s string) int {
 	if len(s) == 0 {
 		return 0
 	}
-	// 扩展 ASCII 码的位图表示（BitSet），共有 256 位
-	var bitSet [256]uint8
+	var bitSet [256]bool
 	result, left, right := 0, 0, 0
 	for left < len(s) {
-		if right < len(s) && bitSet[s[right]] == 0 {
-			// 标记对应的 ASCII 码为 1
-			bitSet[s[right]] = 1
-			right++
-		} else {
-			// 标记对应的 ASCII 码为 0
-			bitSet[s[left]] = 0
+		// 右侧字符对应的bitSet被标记true，说明此字符在X位置重复，需要左侧向前移动，直到将X标记为false
+		if bitSet[s[right]] {
+			bitSet[s[left]] = false
 			left++
+		} else {
+			bitSet[s[right]] = true
+			right++
+		}
+		if result < right-left {
+			result = right - left
+		}
+		if left+result >= len(s) || right >= len(s) {
+			break
 		}
-		result = max(result, right-left)
 	}
 	return result
 }
diff --git a/website/content/ChapterFour/0003.Longest-Substring-Without-Repeating-Characters.md b/website/content/ChapterFour/0003.Longest-Substring-Without-Repeating-Characters.md
index fe3f72072..36e027da8 100644
--- a/website/content/ChapterFour/0003.Longest-Substring-Without-Repeating-Characters.md
+++ b/website/content/ChapterFour/0003.Longest-Substring-Without-Repeating-Characters.md
@@ -60,20 +60,23 @@ func lengthOfLongestSubstring(s string) int {
 	if len(s) == 0 {
 		return 0
 	}
-	// 扩展 ASCII 码的位图表示（BitSet），共有 256 位
-	var bitSet [256]uint8
+	var bitSet [256]bool
 	result, left, right := 0, 0, 0
 	for left < len(s) {
-		if right < len(s) && bitSet[s[right]] == 0 {
-			// 标记对应的 ASCII 码为 1
-			bitSet[s[right]] = 1
-			right++
-		} else {
-			// 标记对应的 ASCII 码为 0
-			bitSet[s[left]] = 0
+		// 右侧字符对应的 bitSet 被标记 true，说明此字符在 X 位置重复，需要左侧向前移动，直到将X标记为 false
+		if bitSet[s[right]] {
+			bitSet[s[left]] = false
 			left++
+		} else {
+			bitSet[s[right]] = true
+			right++
+		}
+		if result < right-left {
+			result = right - left
+		}
+		if left+result >= len(s) || right >= len(s) {
+			break
 		}
-		result = max(result, right-left)
 	}
 	return result
 }