add 49 js solution

Author: swiftwind0405

README.md

@@ -395,7 +395,7 @@
 |52|[N-Queens II](https://leetcode.com/problems/n-queens-ii/)| |Hard|
 |51|[N-Queens](https://leetcode.com/problems/n-queens/)| |Hard|
 |50|["Pow(x, n)"](https://leetcode.com/problems/powx-n/)| |Medium|
-|49|[Group Anagrams](https://leetcode.com/problems/anagrams/)| |Medium|
+|49|[Group Anagrams](https://leetcode.com/problems/anagrams/)| [js](./algorithms/groupAnagrams/solution.js) |Medium|
 |48|[Rotate Image](https://leetcode.com/problems/rotate-image/)| |Medium|
 |47|[Permutations II](https://leetcode.com/problems/permutations-ii/)| |Hard|
 |46|[Permutations](https://leetcode.com/problems/permutations/)| [js](./algorithms/permutations/Solution.js) |Medium|

algorithms/groupAnagrams/solution.js

@@ -0,0 +1,68 @@
+/**
+ * @param {string[]} strs
+ * @return {string[][]}
+ */
+var groupAnagrams = function (strs) {
+    const groupMap = new Map()
+    for (let i = 0; i < strs.length; i++) {
+        console.log(`${i}: 当前处理的字符串：${strs[i]}`)
+        // 查找当前字符串与另外一个字符串是否是字母异位词
+        let exist = false;
+        for (let [key, { group, chatMap }] of groupMap) {
+            console.log('groupMap key: ', key)
+            // 先简单判断长度，不符合直接跳出此次循环
+            if (strs[i].length !== key.length) {
+                console.log('长度不一致继续循环')
+                continue
+            }
+            const _chatMap = new Map(chatMap)
+            for (let j = 0; j < strs[i].length; j++) {
+                const chat = strs[i][j];
+                console.log(`当前查找的字符=>${chat}`)
+                const findChat = _chatMap.has(chat)
+                console.log('findChat:', findChat)
+                if (findChat) {
+                    // 找到了，就把 value - 1
+                    _chatMap.set(chat, _chatMap.get(chat) - 1)
+                    continue
+                }
+                // 找不到则表面不符合，直接跳出循环
+                console.log('不符合条件跳出循环')
+                break
+            }
+            // 判断当前chatMap是否都已经被匹配完
+            if (Array.from(_chatMap.values()).every(item => item === 0)) {
+                console.warn(`===${strs[i]}存在字母异位词${key}===`)
+                // 插入到匹配的group中
+                group.push(strs[i])
+                exist = true
+                break
+            }
+        }
+
+        if (!exist) {
+            // 最后没有匹配的自己成立一组
+            // 创建映射表，value 是各个字符出现次数的映射表 chatMap 和 最终要返回的分组 group
+            // 各个字符出现次数的映射表 chatMap 举例：aabbc => {a => 2, b => 2, c => 1}
+            const chatMap = new Map()
+            strs[i].split('').forEach(s => {
+                chatMap.set(s, chatMap.has(s) ? chatMap.get(s) + 1 : 1)
+            })
+            groupMap.set(strs[i], {
+                group: [strs[i]],
+                chatMap
+            })
+        }
+
+    }
+    return Array.from(groupMap.values()).map(item => item.group);
+};
+
+
+// 输入: strs = ["eat", "tea", "tan", "ate", "nat", "bat"]
+// let strs = ["eat", "tea", "tan", "ate", "nat", "bat"]
+// 输出: [["bat"],["nat","tan"],["ate","eat","tea"]]
+
+// let strs = ["ddddddddddg","dgggggggggg"]
+
+console.log(groupAnagrams(strs))