New Problem Solution - "Mini Parser"

README.md

@@ -11,6 +11,7 @@ LeetCode
 |388|[Longest Absolute File Path](https://leetcode.com/problems/longest-absolute-file-path/) | [C++](./algorithms/cpp/longestAbsoluteFilePath/LongestAbsoluteFilePath.cpp)|Medium|
 |387|[First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/) | [C++](./algorithms/cpp/firstUniqueCharacterInAString/FirstUniqueCharacterInAString.cpp)|Easy|
 |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|
 |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|

algorithms/cpp/miniParser/MiniParser.cpp

@@ -0,0 +1,116 @@
+// Source : https://leetcode.com/problems/mini-parser/
+// Author : Hao Chen
+// Date   : 2016-08-24
+
+/*************************************************************************************** 
+ *
+ * Given a nested list of integers represented as a string, implement a parser to 
+ * deserialize it.
+ * 
+ * Each element is either an integer, or a list -- whose elements may also be integers 
+ * or other lists.
+ * 
+ * Note:
+ * You may assume that the string is well-formed:
+ * 
+ * String is non-empty.
+ * String does not contain white spaces.
+ * String contains only digits 0-9, [, - ,, ].
+ * 
+ * Example 1:
+ * 
+ * Given s = "324",
+ * 
+ * You should return a NestedInteger object which contains a single integer 324.
+ * 
+ * Example 2:
+ * 
+ * Given s = "[123,[456,[789]]]",
+ * 
+ * Return a NestedInteger object containing a nested list with 2 elements:
+ * 
+ * 1. An integer containing value 123.
+ * 2. A nested list containing two elements:
+ *     i.  An integer containing value 456.
+ *     ii. A nested list with one element:
+ *          a. An integer containing value 789.
+ ***************************************************************************************/
+
+
+/**
+ * // This is the interface that allows for creating nested lists.
+ * // You should not implement it, or speculate about its implementation
+ * class NestedInteger {
+ *   public:
+ *     // Constructor initializes an empty nested list.
+ *     NestedInteger();
+ *
+ *     // Constructor initializes a single integer.
+ *     NestedInteger(int value);
+ *
+ *     // Return true if this NestedInteger holds a single integer, rather than a nested list.
+ *     bool isInteger() const;
+ *
+ *     // Return the single integer that this NestedInteger holds, if it holds a single integer
+ *     // The result is undefined if this NestedInteger holds a nested list
+ *     int getInteger() const;
+ *
+ *     // Set this NestedInteger to hold a single integer.
+ *     void setInteger(int value);
+ *
+ *     // Set this NestedInteger to hold a nested list and adds a nested integer to it.
+ *     void add(const NestedInteger &ni);
+ *
+ *     // Return the nested list that this NestedInteger holds, if it holds a nested list
+ *     // The result is undefined if this NestedInteger holds a single integer
+ *     const vector<NestedInteger> &getList() const;
+ * };
+ */
+class Solution {
+public:
+    NestedInteger deserialize(string s) {
+        if (s.size()==0) return NestedInteger();
+        int pos = 0;
+        if (s[pos]!='[') return atoni(s, pos);
+        
+        return helper(s, ++pos);
+    }
+private:
+    NestedInteger helper(string& s, int& pos) {
+       
+        NestedInteger ni;
+        
+        while ( s[pos] != ']' && pos < s.size() ) {
+
+            if (s[pos]=='-' || isnum(s[pos])){
+                ni.add(atoni(s, pos));
+            }else if (s[pos] == '[') {
+                pos++;
+                ni.add(helper(s, pos));
+            }else {
+                pos++;
+            }
+        }
+        pos++;
+        return ni;
+    }
+    NestedInteger atoni(string& s, int& pos) {
+        int sign = 1;
+        int num = 0;
+        if (s[pos]=='-') {
+            sign = -1;
+            pos++;
+        }
+        for (; pos < s.size(); pos++) {
+            if (isnum(s[pos])) {
+                num = num * 10 + s[pos] - '0';
+            }else{
+                break;
+            }
+        }
+        return NestedInteger(sign * num);
+    }
+    bool isnum(char& c) {
+        return (c >='0' && c <='9');
+    }
+};