平衡括号(三)——穿上马甲我就不认识你平衡括号了？

LeetCode_385_MiniParser

题目分析：

分类，递归。
注意cnt变量本质就是在利用平衡括号特性来作为分类依据。

解法：

public static NestedInteger deserialize(String s) {
    if (s.isEmpty()) return new NestedInteger();
    if (s.charAt(0) != '[') return new NestedInteger(Integer.valueOf(s));
    if (s.length() <= 2) return new NestedInteger();
    NestedInteger res = new NestedInteger();
    int start = 1, cnt = 0;
    for (int i = 1; i < s.length(); ++i) {
        if (cnt == 0 && (s.charAt(i) == ',' || i == s.length() - 1)) {
            res.add(deserialize(s.substring(start, i)));
            start = i + 1;
        } else if (s.charAt(i) == '[') ++cnt;
        else if (s.charAt(i) == ']') --cnt;
    }
    return res;
}

public static class NestedInteger {
    List<NestedInteger> childList;
    int val;
    // Constructor initializes an empty nested list.
    public NestedInteger(){
        this.childList = new LinkedList<>();
    }
    // Constructor initializes a single integer.
    public NestedInteger(int value){
        this.val = value;
    }
    // @return true if this NestedInteger holds a single integer, rather than a nested list.
    public boolean isInteger(){
        return 0 == childList.size();
    }
    // @return the single integer that this NestedInteger holds, if it holds a single integer
    // Return null if this NestedInteger holds a nested list
    public Integer getInteger(){
        return val;
    }

    // Set this NestedInteger to hold a single integer.
    public void setInteger(int value){
        this.val = value;
    }

    // Set this NestedInteger to hold a nested list and adds a nested integer to it.
    public void add(NestedInteger ni){
        childList.add(ni);
    }

    // @return the nested list that this NestedInteger holds, if it holds a nested list
    // Return null if this NestedInteger holds a single integer
    public List<NestedInteger> getList(){
        return childList;
    }