https://leetcode.cn/problems/number-of-good-pairs

Author: masx200

README.md

@@ -10,6 +10,8 @@ leetcode 测试
 
 ##### 包含的内容如下
 
+https://leetcode.cn/problems/number-of-good-pairs
+
 https://leetcode.cn/problems/count-unique-characters-of-all-substrings-of-a-given-string
 
 https://leetcode.cn/problems/minimum-height-tree-lcci/

number-of-good-pairs/index.ts

@@ -0,0 +1,11 @@
+export default function numIdenticalPairs(nums: number[]): number {
+    const cnt = new Map<number, number>();
+    for (const num of nums) {
+        cnt.set(num, (cnt.get(num) ?? 0) + 1);
+    }
+    const ans = Array.from(cnt.values()).reduce(
+        (a, v) => a + Math.floor((v * (v - 1)) / 2),
+        0
+    );
+    return ans;
+}