Create 44. 分割回文串.md

Author: jasoncao11

44. 分割回文串.md

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+***给你一个字符串 s，请你将 s 分割成一些子串，使每个子串都是回文串 。返回 s 所有可能的分割方案。***
+
+```
+输入：s = "aab"
+输出：[["a","a","b"],["aa","b"]]
+```
+
+```
+class Solution:
+    def partition(self, s: str) -> List[List[str]]:
+        #双指针判断是否为回文串
+        def ispal(s):
+            left = 0
+            right = len(s)-1
+            while left < right:
+                if s[left] != s[right]:
+                    return False
+                left += 1
+                right -= 1
+            return True
+        #将要遍历的字符串索引
+        ind = 0
+        #当前起始索引
+        start = 0
+        #当前组合
+        cur = []
+        res = []
+        #构造递归
+        def dfs(ind, start, cur):
+            #递归终止条件
+            if ind == len(s):
+                if ''.join(cur) == s:
+                    res.append(cur)
+                return
+            #情况1
+            if ispal(s[start:ind+1]):
+                dfs(ind+1, ind+1, cur+[s[start:ind+1]])
+            #情况2
+            dfs(ind+1, start, cur)
+        #调用递归
+        dfs(ind, start, cur)
+        return res
+```