339 Nested List Weight Sum

Problem:

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.

Example 1: Given the list [[1,1],2,[1,1]], return 10. (four 1's at depth 2, one 2 at depth 1)

Example 2: Given the list [1,[4,[6]]], return 27. (one 1 at depth 1, one 4 at depth 2, and one 6 at depth 3; 1 + 4 * 2 + 6 * 3 = 27)

Solutions:

``````/**
* // This is the interface that allows for creating nested lists.
* // You should not implement it, or speculate about its implementation
* public interface NestedInteger {
*
*     // @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();
*
*     // @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 depthSum(List<NestedInteger> nestedList) {
return ds(1, nestedList);
}
private int ds(int level, List<NestedInteger> nestedList) {
int sum = 0;
for (NestedInteger ni:nestedList) {
if (ni.isInteger()) {
sum +=level * ni.getInteger();
}
else {
sum +=ds(level + 1, ni.getList());
}
}
return sum;
}
}
``````
``````/**
* // 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.
*
*     // @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();
* }
*/
class Solution {
public int depthSum(List<NestedInteger> nestedList) {
for (NestedInteger ni:nestedList) {
}
int count = 0;
while (!q.isEmpty()) {
NestedInteger ni = q.poll();
int weight = w.poll();
if (ni.isInteger()) {
count += ni.getInteger() * weight;
continue;
}
for (NestedInteger n:ni.getList()) {