645. 错误的集合

Author: w2xi

README.md

@@ -81,6 +81,7 @@
 |617|[合并二叉树](https://leetcode.cn/problems/merge-two-binary-trees/)|[JavaScript](./algorithms/merge-two-binary-trees.js)|Easy|
 |628|[三个数的最大乘积](https://leetcode.cn/problems/maximum-product-of-three-numbers/)|[JavaScript](./algorithms/maximum-product-of-three-numbers.js)|Easy|
 |637|[二叉树的层平均值](https://leetcode.cn/problems/average-of-levels-in-binary-tree/)|[JavaScript](./algorithms/average-of-levels-in-binary-tree.js)|Easy|
+|645|[错误的集合](https://leetcode.cn/problems/set-mismatch/)|[JavaScript](./algorithms/set-mismatch.js)||Easy|
 |687|[最长同值路径](https://leetcode.cn/problems/longest-univalue-path/)|[JavaScript](./algorithms/longest-univalue-path.js)|Medium|
 |700|[二叉搜索树中的搜索](https://leetcode.cn/problems/search-in-a-binary-search-tree/)|[JavaScript](./algorithms/search-in-a-binary-search-tree.js)|Easy|
 |704|[二分查找](https://leetcode.cn/problems/binary-search/)|[JavaScript](./algorithms/binary-search.js)|Easy|

algorithms/set-mismatch.js

@@ -0,0 +1,35 @@
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var findErrorNums = function (nums) {
+  const map = new Map();
+  const result = [];
+
+  // 思路:
+  // 在「哈希表」中出现 2 次的为重复元素，未在「哈希表」中出现的元素为缺失元素
+  // 在 [1, n] 中查询未出现的元素
+
+  // 统计每个数出现的次数
+  for (let i = 0; i < nums.length; i++) {
+    const curr = nums[i];
+    if (map.has(curr)) {
+      const count = map.get(curr);
+      map.set(curr, count + 1);
+      // 重复元素
+      result.push(curr);
+    } else {
+      map.set(curr, 1);
+    }
+  }
+
+  for (let i = 1; i <= nums.length; i++) {
+    if (!map.has(i)) {
+      // 缺失元素
+      result.push(i);
+      break;
+    }
+  }
+
+  return result;
+};