diff --git a/problems/0056.合并区间.md b/problems/0056.合并区间.md
index 93c0a2a0..fd914497 100644
--- a/problems/0056.合并区间.md
+++ b/problems/0056.合并区间.md
@@ -241,6 +241,32 @@ var merge = function (intervals) {
     return result
 };
 ```
+版本二：左右区间
+```javascript
+/**
+ * @param {number[][]} intervals
+ * @return {number[][]}
+ */
+var merge = function(intervals) {
+    let n = intervals.length;
+    if ( n < 2) return intervals;
+    intervals.sort((a, b) => a[0]- b[0]);
+    let res = [],
+        left = intervals[0][0],
+        right = intervals[0][1];
+    for (let i = 1; i < n; i++) {
+        if (intervals[i][0] > right) {
+            res.push([left, right]);
+            left = intervals[i][0];
+            right = intervals[i][1];
+        } else {
+            right = Math.max(intervals[i][1], right);
+        }
+    }
+    res.push([left, right]);
+    return res;
+};
+```