程式語言 - LeetCode - C++ - 385. Mini Parser


參考資訊：
https://www.cnblogs.com/grandyang/p/5771434.html

題目：


解答： 

/**
 * // 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[0] != '[') {
            return NestedInteger(stoi(s));
        }

        stack<NestedInteger> st;
        int n = s.size();
        int num = 0;
        bool negative = false;

        for (int i = 0; i < n; ++i) {
            char c = s[i];

            if (c == '[') {
                st.push(NestedInteger());
            }
            else if (c == '-') {
                negative = true;
            }
            else if (isdigit(c)) {
                num = (num * 10) + (c - '0');
            }
            else if (c == ',' || c == ']') {
                if (isdigit(s[i - 1])) {
                    if (negative) {
                        num = -num;
                    }
                    st.top().add(NestedInteger(num));
                }

                num = 0;
                negative = false;
                if (c == ']' && st.size() > 1) {
                    NestedInteger n = st.top();
                    st.pop();
                    st.top().add(n);
                }
            }
        }

        return st.top();
    }
};