Merge pull request algorithm004-01#407 from IATF/master

melody-li · web-flow · commit 8ec437f2e960 · 2019-10-28T11:57:53.000+08:00
381-Week 02
diff --git a/Week 02/id_381/leetcode-1.py b/Week 02/id_381/leetcode-1.py
@@ -0,0 +1,9 @@
+class Solution:
+    def twoSum(self, nums: list, target: int) -> list:
+        tmp_dict = {}
+        for i in range(len(nums)):
+            sub = target - nums[i]
+            if sub in tmp_dict:
+                if tmp_dict[sub] != i:
+                    return [i, tmp_dict[sub]]
+            tmp_dict[nums[i]] = i
diff --git a/Week 02/id_381/leetcode-242.py b/Week 02/id_381/leetcode-242.py
@@ -0,0 +1,24 @@
+"""
+两字符串各个字符数量相减为0
+"""
+
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        # 长度不等，直接返回False
+        if len(s) != len(t):
+            return False
+        counter = {}
+        for i in s:
+            if i not in counter:
+                counter[i] = 1
+            else:
+                counter[i] += 1
+        for j in t:
+            if j not in counter:
+                return False
+            counter[j] -= 1
+        # 查看最后的结果是否为0
+        for key, value in counter.items():
+            if value != 0:
+                return False
+        return True
diff --git a/Week 02/id_381/leetcode-49.py b/Week 02/id_381/leetcode-49.py
@@ -0,0 +1,9 @@
+from collections import defaultdict
+class Solution:
+    def groupAnagrams(self, strs: list) -> list:
+        tmp_dict = defaultdict(list)
+        for i, item in enumerate(strs):
+            tmp = ''.join(sorted(item))
+            # 与上面的相比，这里直接加上item会更好
+            tmp_dict[tmp].append(item)
+        return tmp_dict.values()
diff --git a/Week 02/id_381/leetcode-94.py b/Week 02/id_381/leetcode-94.py
@@ -0,0 +1,14 @@
+class Solution:
+    def inorderTraversal(self, root) -> list:
+        data = []
+        stack = []
+        current = root
+        # 需要注意current和stack同时为None的时候才能跳出循环
+        while current or stack:
+            while current:
+                stack.append(current)
+                current = current.left
+            pop_node = stack.pop()
+            data.append(pop_node.val)
+            current = pop_node.right
+        return data
