LeetCode #339 - Nested List Weight Sum

LawFile

于 2019-01-30 01:56:50 发布

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本文介绍了一种针对嵌套整数列表的深度加权求和算法，通过递归方式计算列表中每个整数的值，该值等于其数值乘以其在列表中的深度。文章通过两个示例详细解释了算法的运行过程。

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题目描述：

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:

Input: [[1,1],2,[1,1]]

Output: 10

Explanation: Four 1's at depth 2, one 2 at depth 1.

Example 2:

Input: [1,[4,[6]]]

Output: 27

Explanation: One 1 at depth 1, one 4 at depth 2, and one 6 at depth 3; 1 + 4*2 + 6*3 = 27.

每个数的值是它数值乘以层数，所以用递归的解法就很简单了。

class Solution {
public:
    int depthSum(vector<NestedInteger>& nestedList) 
    {
        int res=0;
        for (auto a : nestedList) {
            res+=getSum(a, 1);
        }
        return res;
    }
    int getSum(NestedInteger x, int level) 
    {
        int res=0;
        if (x.isInteger()) return level*x.getInteger();
        for (auto a: x.getList()) {
            res+=getSum(a, level+1);
        }
        return res;
    }
};