New Problem Solution - "Ransom Note"

haoel · haoel · commit d61801b8ba43 · 2016-08-24T13:24:30.000+08:00
diff --git a/README.md b/README.md
@@ -13,6 +13,7 @@ LeetCode
 |386|[Lexicographical Numbers](https://leetcode.com/problems/lexicographical-numbers/) | [C++](./algorithms/cpp/lexicographicalNumbers/LexicographicalNumbers.cpp)|Medium|
 |385|[Mini Parser](https://leetcode.com/problems/mini-parser/) | [C++](./algorithms/cpp/miniParser/MiniParser.cpp)|Medium|
 |384|[Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/) | [C++](./algorithms/cpp/shuffleAnArray/ShuffleAnArray.cpp)|Medium|
+|383|[Ransom Note](https://leetcode.com/problems/ransom-note/) | [C++](./algorithms/cpp/ransomNote/RansomNote.cpp)|Easy|
 |377|[Combination Sum IV](https://leetcode.com/problems/combination-sum-iv/) | [C++](./algorithms/cpp/combinationSumIV/combinationSumIV.cpp)|Medium|
 |376|[Wiggle Subsequence](https://leetcode.com/problems/wiggle-subsequence/) | [C++](./algorithms/cpp/wiggleSubsequence/wiggleSubsequence.cpp)|Medium|
 |350|[Intersection of Two Arrays II](https://leetcode.com/problems/intersection-of-two-arrays-ii/) | [C++](./algorithms/cpp/intersectionOfTwoArraysII/intersectionOfTwoArraysII.cpp)|Easy|
diff --git a/algorithms/cpp/ransomNote/RansomNote.cpp b/algorithms/cpp/ransomNote/RansomNote.cpp
@@ -0,0 +1,38 @@
+// Source : https://leetcode.com/problems/ransom-note/
+// Author : Hao Chen
+// Date   : 2016-08-24
+
+/*************************************************************************************** 
+ *
+ *  Given  an  arbitrary  ransom  note  string  and  another  string  containing 
+ *  letters from  all  the  magazines,  write  a  function  that  will  return  true 
+ *  if  the  ransom  
+ * note  can  be  constructed  from  the  magazines ;  otherwise,  it  will  return 
+ *  false.   
+ * 
+ * Each  letter  in  the  magazine  string  can  only  be  used  once  in  your 
+ *  ransom  note.
+ * 
+ * Note:
+ * You may assume that both strings contain only lowercase letters.
+ * 
+ * canConstruct("a", "b") -> false
+ * canConstruct("aa", "ab") -> false
+ * canConstruct("aa", "aab") -> true
+ ***************************************************************************************/
+
+class Solution {
+public:
+    bool canConstruct(string ransomNote, string magazine) {
+        unordered_map<char, int> m;
+        for(int i=0; i<magazine.size(); i++) {
+            m[magazine[i]]++;
+        }
+        for (int i=0; i<ransomNote.size(); i++) {
+            char c = ransomNote[i];
+            if (m[c] <=0 ) return false;
+            m[c]--;
+        }
+        return true;
+    }
+};
