Leetcode 364 Nested List Weight Sum II

Given a nested list of integers, return the sum of all integers in the list weighted by their depth.

Each element is either an integer, or a list -- whose elements may also be integers or other lists.

Different from the previous question where weight is increasing from root to leaf, now the weight
is defined from bottom up. i.e., the leaf level integers have weight 1, and the root level integers have the largest weight.

Example 1:

Given the list 

[[1,1],2,[1,1]]

, return 8. (four 1's
at depth 1, one 2 at depth 2)

Example 2:

Given the list 

[1,[4,[6]]]

, return 17. (one 1
at depth 3, one 4 at depth 2, and one 6 at depth 1; 1*3 + 4*2 + 6*1 = 17)

这个我真的没头绪了 = =

要把权重倒过来

先献上我的膝盖。。。我真的没想到一个问题，最外层的需要权重最大 可以通过每层遍历时反复叠加实现

/**
* // This is the interface that allows for creating nested lists.
* // You should not implement it, or speculate about its implementation
* public interface NestedInteger {
* // Constructor initializes an empty nested list.
* public NestedInteger();
*
* // Constructor initializes a single integer.
* public NestedInteger(int value);
*
* // @return true if this NestedInteger holds a single integer, rather than a nested list.
* public boolean isInteger();
*
* // @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();
*
* // Set this NestedInteger to hold a single integer.
* public void setInteger(int value);
*
* // Set this NestedInteger to hold a nested list and adds a nested integer to it.
* public void add(NestedInteger 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();
* }
*/
public class Solution {
public int depthSumInverse(List<NestedInteger> nestedList) {
if (nestedList == null) return 0;
Queue<NestedInteger> queue = new LinkedList<NestedInteger>();
int prev = 0;
int total = 0;
for (NestedInteger next: nestedList) {
queue.offer(next);
}

while (!queue.isEmpty()) {
int size = queue.size();
int levelSum = 0;
for (int i = 0; i < size; i++) {
NestedInteger current = queue.poll();
if (current.isInteger()) levelSum += current.getInteger();
List<NestedInteger> nextList = current.getList();
if (nextList != null) {
for (NestedInteger next: nextList) {
queue.offer(next);
}
}
}
prev += levelSum;
total += prev;
}
return total;
}
}