Merge pull request youngyangyang04#1973 from Projecthappy/master

优化0454.四数相加II中 java的方法
nowsoar · Apr 6, 2023 · 2ff490e · 2ff490e
2 parents 27ae005 + 6dd7f42
commit 2ff490e
Showing 1 changed file with 8 additions and 9 deletions.
diff --git a/problems/0454.四数相加II.md b/problems/0454.四数相加II.md
@@ -97,26 +97,25 @@ 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;
+        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
         //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);
+                int tmp = map.getOrDefault(i + j, 0);
+                if (tmp == 0) {
+                    map.put(i + j, 1);
                 } else {
-                    map.put(temp, 1);
+                    map.replace(i + j, tmp + 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);
+                int tmp = map.getOrDefault(0 - i - j, 0);
+                if (tmp != 0) {
+                    res += tmp;
                 }
             }
         }