solve problem Ransom Note

Author: P-ppc

README.md

@@ -45,6 +45,7 @@ All solutions will be accepted!
 |145|[Binary Tree Postorder Traversal](https://leetcode-cn.com/problems/binary-tree-postorder-traversal/description/)|[java/py/js](./algorithms/BinaryTreePostorderTraversal)|Hard|
 |231|[Power Of Two](https://leetcode-cn.com/problems/power-of-two/description/)|[java/py/js](./algorithms/PowerOfTwo)|Easy|
 |38|[Count And Say](https://leetcode-cn.com/problems/count-and-say/description/)|[java/py/js](./algorithms/CountAndSay)|Easy|
+|383|[Ransom Note](https://leetcode-cn.com/problems/ransom-note/description/)|[java/py/js](./algorithms/RansomNote)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/RansomNote/README.md

@@ -0,0 +1,2 @@
+# Ransom Note
+This problem is easy to solve by hashmap

algorithms/RansomNote/Solution.java

@@ -0,0 +1,21 @@
+class Solution {
+    public boolean canConstruct(String ransomNote, String magazine) {
+        Map<Character, Integer> characterMap = new HashMap<Character, Integer>();
+        for (char c : magazine.toCharArray()) {
+            if (characterMap.get(c) == null) {
+                characterMap.put(c, 1);
+            } else {
+                characterMap.put(c, characterMap.get(c) + 1);
+            }
+        }
+        
+        for (char c: ransomNote.toCharArray()) {
+            if (characterMap.get(c) == null || characterMap.get(c) == 0) {
+                return false;
+            } else {
+                characterMap.put(c, characterMap.get(c) - 1);
+            }
+        }
+        return true;
+    }
+}

algorithms/RansomNote/solution.js

@@ -0,0 +1,27 @@
+/**
+ * @param {string} ransomNote
+ * @param {string} magazine
+ * @return {boolean}
+ */
+var canConstruct = function(ransomNote, magazine) {
+    let characterMap = {}
+    for (let i = 0; i < magazine.length; i++) {
+        let c = magazine[i]
+        if (characterMap[c] !== undefined) {
+            characterMap[c] += 1
+        } else {
+            characterMap[c] = 1
+        }
+    }
+    
+    for (let i = 0; i < ransomNote.length; i++) {
+        let c = ransomNote[i]
+        if (characterMap[c] === undefined || characterMap[c] === 0) {
+            return false
+        } else {
+            characterMap[c] -= 1
+        }
+    }
+    
+    return true
+};

algorithms/RansomNote/solution.py

@@ -0,0 +1,21 @@
+class Solution(object):
+    def canConstruct(self, ransomNote, magazine):
+        """
+        :type ransomNote: str
+        :type magazine: str
+        :rtype: bool
+        """
+        character_map = {}
+        for c in magazine:
+            if character_map.get(c) != None:
+                character_map[c] += 1
+            else:
+                character_map[c] = 1
+                
+        for c in ransomNote:
+            if character_map.get(c) == None or character_map.get(c) == 0:
+                return False
+            else:
+                character_map[c] -= 1
+        return True
+