From fab96e6c482e14c5b576aeef48fd1046d9bf45fc Mon Sep 17 00:00:00 2001
From: nanhuaibeian <49868746+nanhuaibeian@users.noreply.github.com>
Date: Wed, 12 May 2021 20:56:06 +0800
Subject: [PATCH] =?UTF-8?q?Update=200454.=E5=9B=9B=E6=95=B0=E7=9B=B8?=
 =?UTF-8?q?=E5=8A=A0II.md?=
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---
 problems/0454.四数相加II.md | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/problems/0454.四数相加II.md b/problems/0454.四数相加II.md
index 71dcc1ae..a2ef928b 100644
--- a/problems/0454.四数相加II.md
+++ b/problems/0454.四数相加II.md
@@ -88,7 +88,36 @@ public:
 
 
 Java：
-
+```Java
+class Solution {
+    public int fourSumCount(int[] nums1, int[] nums2, int[] nums3, int[] nums4) {
+        Map<Integer, Integer> map = new HashMap<>();
+        int temp;
+        int res = 0;
+        //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) {
+                temp = i + j;
+                if (map.containsKey(temp)) {
+                    map.put(temp, map.get(temp) + 1);
+                } else {
+                    map.put(temp, 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) {
+                temp = i + j;
+                if (map.containsKey(0 - temp)) {
+                    res += map.get(0 - temp);
+                }
+            }
+        }
+        return res;
+    }
+}
+```
 
 Python：