add 1679

fishercoder1534 · fishercoder1534 · commit 60ab030edc04 · 2020-12-06T10:26:41.000-08:00
diff --git a/README.md b/README.md
@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ &#9733;
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1679|[Max Number of K-Sum Pairs](https://leetcode.com/problems/max-number-of-k-sum-pairs/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1679.java) ||Medium|HashTable|
 |1678|[Goal Parser Interpretation](https://leetcode.com/problems/goal-parser-interpretation/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1678.java) ||Easy|String|
 |1673|[Find the Most Competitive Subsequence](https://leetcode.com/problems/find-the-most-competitive-subsequence/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1673.java) ||Medium|Stack, Greedy|
 |1672|[Richest Customer Wealth](https://leetcode.com/problems/richest-customer-wealth/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1672.java) ||Easy|Array|
diff --git a/src/main/java/com/fishercoder/solutions/_1679.java b/src/main/java/com/fishercoder/solutions/_1679.java
@@ -0,0 +1,25 @@
+package com.fishercoder.solutions;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class _1679 {
+    public static class Solution1 {
+        public int maxOperations(int[] nums, int k) {
+            Map<Integer, Integer> map = new HashMap<>();
+            int ops = 0;
+            for (int num : nums) {
+                if (map.containsKey(k - num)) {
+                    map.put(k - num, map.get(k - num) - 1);
+                    ops++;
+                    if (map.get(k - num) == 0) {
+                        map.remove(k - num);
+                    }
+                } else {
+                    map.put(num, map.getOrDefault(num, 0) + 1);
+                }
+            }
+            return ops;
+        }
+    }
+}
