LeetCode 339. 嵌套列表权重和（DFS）

示例 1:
输入: [[1,1],2,[1,1]]
输出: 10 
解释: 因为列表中有四个深度为 2 的 1 ，和一个深度为 1 的 2。

示例 2:
输入: [1,[4,[6]]]
输出: 27 
解释: 一个深度为 1 的 1，一个深度为 2 的 4，一个深度为 3 的 6。
所以，1 + 4*2 + 6*3 = 27。

/**
 * // 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 {
	int ans = 0;
public:
    int depthSum(vector<NestedInteger>& nestedList) {
    	if(nestedList.empty()) return 0;
    	dfs(nestedList,1);
    	return ans;
    }
    void dfs(vector<NestedInteger> &nestedList, int deep)
    {
    	for(int i = 0; i < nestedList.size(); ++i)
    	{
    		if(nestedList[i].isInteger())
    			ans += nestedList[i].getInteger() * deep;
    		else
    			dfs(nestedList[i].getList(),deep+1);
    	}
    }
};