Leetcode: Nested List Weight Sum

最新推荐文章于 2020-04-02 13:00:12 发布

转载最新推荐文章于 2020-04-02 13:00:12 发布 · 99 阅读

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原文链接：http://www.cnblogs.com/EdwardLiu/p/6181814.html

本文介绍了一种针对嵌套整数列表的深度加权求和算法，通过递归遍历列表并根据元素的深度计算其加权和。示例包括了如何处理不同深度的整数列表。

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)

DFS:

 1 /**
 2  * // This is the interface that allows for creating nested lists.
 3  * // You should not implement it, or speculate about its implementation
 4  * public interface NestedInteger {
 5  *
 6  *     // @return true if this NestedInteger holds a single integer, rather than a nested list.
 7  *     public boolean isInteger();
 8  *
 9  *     // @return the single integer that this NestedInteger holds, if it holds a single integer
10  *     // Return null if this NestedInteger holds a nested list
11  *     public Integer getInteger();
12  *
13  *     // @return the nested list that this NestedInteger holds, if it holds a nested list
14  *     // Return null if this NestedInteger holds a single integer
15  *     public List<NestedInteger> getList();
16  * }
17  */
18 public class Solution {
19     public int depthSum(List<NestedInteger> nestedList) {
20         return depthSum(nestedList, 1);
21     }
22     
23     public int depthSum(List<NestedInteger> nestedList, int weight) {
24         int sum = 0;
25         for (NestedInteger each : nestedList) {
26             if (each.isInteger()) 
27                 sum += each.getInteger() * weight;
28             else sum += depthSum(each.getList(), weight+1);
29         }
30         return sum;
31     }
32 }

转载于:https://www.cnblogs.com/EdwardLiu/p/6181814.html