diff --git a/problems/0383.赎金信.md b/problems/0383.赎金信.md
index d9a184b6..a3f87d4a 100644
--- a/problems/0383.赎金信.md
+++ b/problems/0383.赎金信.md
@@ -117,6 +117,10 @@ Java：
 ```Java
 class Solution {
     public boolean canConstruct(String ransomNote, String magazine) {
+        // shortcut
+        if (ransomNote.length() > magazine.length()) {
+            return false;
+        }
         // 定义一个哈希映射数组
         int[] record = new int[26];
 
diff --git a/problems/0454.四数相加II.md b/problems/0454.四数相加II.md
index 411b60e8..abfc7c23 100644
--- a/problems/0454.四数相加II.md
+++ b/problems/0454.四数相加II.md
@@ -102,21 +102,14 @@ class Solution {
         //统计两个数组中的元素之和，同时统计出现的次数，放入map
         for (int i : nums1) {
             for (int j : nums2) {
-                int tmp = map.getOrDefault(i + j, 0);
-                if (tmp == 0) {
-                    map.put(i + j, 1);
-                } else {
-                    map.replace(i + j, tmp + 1);
-                }
+                int sum = i + j;
+                map.put(sum, map.getOrDefault(sum, 0) + 1);
             }
         }
         //统计剩余的两个元素的和，在map中找是否存在相加为0的情况，同时记录次数
         for (int i : nums3) {
             for (int j : nums4) {
-                int tmp = map.getOrDefault(0 - i - j, 0);
-                if (tmp != 0) {
-                    res += tmp;
-                }
+                res += map.getOrDefault(0 - i - j, 0);
             }
         }
         return res;