Update 454.4-sum-ii.md

Author: azl397985856

problems/454.4-sum-ii.md

@@ -47,6 +47,8 @@ The two tuples are:
 - 两两分组，求出两两结合能够得出的可能数，然后合并即可。
 
 ## 代码
+
+语言支持： `JavaScript`，`Python3`
 ```js
 
 /*
@@ -55,41 +57,6 @@ The two tuples are:
  * [454] 4Sum II
  *
  * https://leetcode.com/problems/4sum-ii/description/
- *
- * algorithms
- * Medium (49.93%)
- * Total Accepted:    63.2K
- * Total Submissions: 125.6K
- * Testcase Example:  '[1,2]\n[-2,-1]\n[-1,2]\n[0,2]'
- *
- * Given four lists A, B, C, D of integer values, compute how many tuples (i,
- * j, k, l) there are such that A[i] + B[j] + C[k] + D[l] is zero.
- *
- * To make problem a bit easier, all A, B, C, D have same length of N where 0 ≤
- * N ≤ 500. All integers are in the range of -2^28 to 2^28 - 1 and the result
- * is guaranteed to be at most 2^31 - 1.
- *
- * Example:
- *
- *
- * Input:
- * A = [ 1, 2]
- * B = [-2,-1]
- * C = [-1, 2]
- * D = [ 0, 2]
- *
- * Output:
- * 2
- *
- * Explanation:
- * The two tuples are:
- * 1. (0, 0, 0, 1) -> A[0] + B[0] + C[0] + D[1] = 1 + (-2) + (-1) + 2 = 0
- * 2. (1, 1, 0, 0) -> A[1] + B[1] + C[0] + D[0] = 2 + (-1) + (-1) + 0 = 0
- *
- *
- *
- *
- */
 /**
  * @param {number[]} A
  * @param {number[]} B
@@ -115,3 +82,18 @@ var fourSumCount = function(A, B, C, D) {
   return res;
 };
 ```
+
+```python
+class Solution:
+    def fourSumCount(self, A: List[int], B: List[int], C: List[int], D: List[int]) -> int:
+        mapper = {}
+        res = 0
+        for i in A:
+            for j in B:
+                mapper[i + j] = mapper.get(i + j, 0) + 1
+        
+        for i in C:
+            for j in D:
+                res += mapper.get(-1 * (i + j), 0)
+        return res
+ ```