Update 0383.赎金信.md

Author: jianghongcheng

problems/0383.赎金信.md

@@ -142,94 +142,70 @@ class Solution {
 
 ```
 
-Python写法一（使用数组作为哈希表）：
-
+（版本一）使用数组
 ```python
 class Solution:
     def canConstruct(self, ransomNote: str, magazine: str) -> bool:
-
-        arr = [0] * 26
-
-        for x in magazine:    # 记录 magazine里各个字符出现次数
-            arr[ord(x) - ord('a')] += 1
-
-        for x in ransomNote:  # 在arr里对应的字符个数做--操作
-            if arr[ord(x) - ord('a')] == 0:  # 如果没有出现过直接返回
-                return False
-            else:
-                arr[ord(x) - ord('a')] -= 1
-        
-        return True
+        ransom_count = [0] * 26
+        magazine_count = [0] * 26
+        for c in ransomNote:
+            ransom_count[ord(c) - ord('a')] += 1
+        for c in magazine:
+            magazine_count[ord(c) - ord('a')] += 1
+        return all(ransom_count[i] <= magazine_count[i] for i in range(26))
 ```
 
-Python写法二（使用defaultdict）：
+（版本二）使用defaultdict
 
 ```python
+from collections import defaultdict
+
 class Solution:
     def canConstruct(self, ransomNote: str, magazine: str) -> bool:
 
-        from collections import defaultdict
-
         hashmap = defaultdict(int)
 
         for x in magazine:
             hashmap[x] += 1
 
         for x in ransomNote:
             value = hashmap.get(x)
-            if value is None or value == 0:
+            if not value or not value:
                 return False
             else:
                 hashmap[x] -= 1
 
         return True
 ```
-
-Python写法三：
+（版本三）使用字典
 
 ```python
-class Solution(object):
-    def canConstruct(self, ransomNote, magazine):
-        """
-        :type ransomNote: str
-        :type magazine: str
-        :rtype: bool
-        """
-        
-        # use a dict to store the number of letter occurance in ransomNote
-        hashmap = dict()
-        for s in ransomNote:
-            if s in hashmap:
-                hashmap[s] += 1
-            else:
-                hashmap[s] = 1
-        
-        # check if the letter we need can be found in magazine
-        for l in magazine:
-            if l in hashmap:
-                hashmap[l] -= 1
-        
-        for key in hashmap:
-            if hashmap[key] > 0:
+class Solution:
+    def canConstruct(self, ransomNote: str, magazine: str) -> bool:
+        counts = {}
+        for c in magazine:
+            counts[c] = counts.get(c, 0) + 1
+        for c in ransomNote:
+            if c not in counts or counts[c] == 0:
                 return False
-        
+            counts[c] -= 1
         return True
 ```
+（版本四）使用Counter
 
-Python写法四：
+```python
+from collections import Counter
+
+class Solution:
+    def canConstruct(self, ransomNote: str, magazine: str) -> bool:
+        return not Counter(ransomNote) - Counter(magazine)
+```
+（版本五）使用count
 
 ```python
 class Solution:
     def canConstruct(self, ransomNote: str, magazine: str) -> bool:
-        c1 = collections.Counter(ransomNote)
-        c2 = collections.Counter(magazine)
-        x = c1 - c2
-        #x只保留值大于0的符号，当c1里面的符号个数小于c2时，不会被保留
-        #所以x只保留下了，magazine不能表达的
-        if(len(x)==0):
-            return True
-        else:
-            return False
+        return all(ransomNote.count(c) <= magazine.count(c) for c in set(ransomNote))
 ```
 
 Go：