Intersection Of Two Arrays

Author: w2xi

README.md

@@ -8,4 +8,5 @@
 |9|[回文数](https://leetcode-cn.com/problems/palindrome-number/)|[JavaScript](./algorithms/palindrome-number.js)|Easy|
 |14|[最长公共前缀](https://leetcode-cn.com/problems/longest-common-prefix/)|[JavaScript](./algorithms/longest-common-prefix.js)|Easy|
 |21|[合并两个有序链表](https://leetcode-cn.com/problems/merge-two-sorted-lists/)|[JavaScript](./algorithms/merge-two-sorted-lists.js)|Easy|
-|189|[轮转数组](https://leetcode-cn.com/problems/rotate-array/)|[JavaScript](./algorithms/rotate-array.js)|Medium|
+|189|[轮转数组](https://leetcode-cn.com/problems/rotate-array/)|[JavaScript](./algorithms/rotate-array.js)|Medium|
+|349|[两个数组的交集](https://leetcode-cn.com/problems/intersection-of-two-arrays/)|[JavaScript](./algorithms/intersection-of-two-arrays.js)|Easy|

algorithms/intersection-of-two-arrays.js

@@ -0,0 +1,63 @@
+/**
+ * @param {number[]} nums1
+ * @param {number[]} nums2
+ * @return {number[]}
+ */
+
+// 方法一：映射（降低时间复杂度）
+var intersection = function (nums1, nums2) {
+  const result = [];
+  const nums2Obj = {};
+  // 保存出现过的值
+  const occured = {};
+
+  for (let i = 0; i < nums2.length; i++) {
+    nums2Obj[nums2[i]] = true;
+  }
+
+  for (let i = 0; i < nums1.length; i++) {
+    const curr = nums1[i];
+
+    if (nums2Obj[curr] && !occured[curr]) {
+      occured[curr] = true;
+
+      result.push(nums1[i]);
+    }
+  }
+
+  return result;
+};
+
+// 方法二：排序 + 双指针
+var intersection = function (nums1, nums2) {
+  nums1.sort((a, b) => a - b);
+  nums2.sort((a, b) => a - b);
+
+  let len1 = nums1.length;
+  let len2 = nums2.length;
+  let l1, l2, result = [];
+  l1 = l2 = 0;
+
+  // 上一次出现相等的数字
+  let lastEqualNumber;
+
+  while (l1 < len1 && l2 < len2) {
+    if (nums1[l1] < nums2[l2]) {
+      l1++;
+    } else if (nums1[l1] > nums2[l2]) {
+      l2++;
+    } else {
+      const curr = nums1[l1];
+
+      if (curr !== lastEqualNumber) {
+        result.push(curr);
+      }
+
+      lastEqualNumber = curr;
+      l1++;
+      l2++;
+    }
+  }
+
+  return result;
+};