add 923

fishercoder1534 · fishercoder1534 · commit 7203cf738e25 · 2021-03-23T08:41:52.000-07:00
diff --git a/README.md b/README.md
@@ -396,6 +396,7 @@ _If you like this project, please leave me a star._ &#9733;
 |931|[Minimum Falling Path Sum](https://leetcode.com/problems/minimum-falling-path-sum/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_931.java) | |Medium|Dynamic Programming
 |929|[Unique Email Addresses](https://leetcode.com/problems/unique-email-addresses/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_929.java) | |Easy|
 |925|[Long Pressed Name](https://leetcode.com/problems/long-pressed-name/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_925.java) | |Easy|
+|923|[3Sum With Multiplicity](https://leetcode.com/problems/3sum-with-multiplicity/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_923.java) | |Medium|Two Pointers
 |922|[Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_922.java) |  |Easy|
 |921|[Minimum Add to Make Parentheses Valid](https://leetcode.com/problems/minimum-add-to-make-parentheses-valid/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_921.java) | |Medium|Stack, Greedy
 |917|[Reverse Only Letters](https://leetcode.com/problems/reverse-only-letters/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_917.java) |  |Easy|
diff --git a/src/main/java/com/fishercoder/solutions/_923.java b/src/main/java/com/fishercoder/solutions/_923.java
@@ -0,0 +1,35 @@
+package com.fishercoder.solutions;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class _923 {
+    public static class Solution1 {
+        public int threeSumMulti(int[] A, int target) {
+            int MOD = 1000000007;
+            Map<Integer, Long> map = new HashMap<>();
+            for (int num : A) {
+                map.put(num, map.getOrDefault(num, 0L) + 1);
+            }
+            long result = 0;
+            for (int num1 : map.keySet()) {
+                for (int num2 : map.keySet()) {
+                    int num3 = target - num1 - num2;
+                    if (map.containsKey(num3)) {
+                        Long count1 = map.get(num1);
+                        Long count2 = map.get(num2);
+                        Long count3 = map.get(num3);
+                        if (num1 == num2 && num1 == num3) {
+                            result = (result + (count1 * (count1 - 1) * (count1 - 2) / 6)) % MOD;
+                        } else if (num1 == num2 && num1 != num3) {
+                            result = (result + (count1 * (count1 - 1) / 2) * count3) % MOD;
+                        } else if (num1 < num2 && num2 < num3) {
+                            result = (result + count1 * count2 * count3) % MOD;
+                        }
+                    }
+                }
+            }
+            return (int) result;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_923Test.java b/src/test/java/com/fishercoder/_923Test.java
@@ -0,0 +1,21 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._923;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _923Test {
+    private static _923.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _923.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(20, solution1.threeSumMulti(new int[]{1, 1, 2, 2, 3, 3, 4, 4, 5, 5}, 8));
+    }
+}
