385 Mini Parser 迷你解析器

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.
详见：https://leetcode.com/problems/mini-parser/description/

C++：

/**
 * // 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.empty())
        {
            return NestedInteger();
        }
        if(s[0]!='[')
        {
            return NestedInteger(stoi(s));
        }
        if(s.size()<=2)
        {
            return NestedInteger();
        }
        NestedInteger res;
        int cnt=0;
        int start=1;
        for(int i=1;i<s.size();++i)
        {
            if(cnt==0&&s[i]==','||i==s.size()-1)
            {
                res.add(deserialize(s.substr(start,i-start)));
                start=i+1;
            }
            else if(s[i]=='[')
            {
                ++cnt;
            }
            else if(s[i]==']')
            {
                --cnt;
            }
        }
        return res;
    }
};

参考：https://www.cnblogs.com/grandyang/p/5771434.html