LeetCode #364. Nested List Weight Sum II

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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，该算法从底部向上计算权重，使得叶级整数权重为1，根级整数具有最大权重。通过两个示例展示了算法的具体应用，包括计算过程和最终结果。

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.

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:

Input: [[1,1],2,[1,1]]
Output: 8 
Explanation: Four 1's at depth 1, one 2 at depth 2.

Example 2:

Input: [1,[4,[6]]]
Output: 17 
Explanation: One 1 at depth 3, one 4 at depth 2, and one 6 at depth 1; 1*3 + 4*2 + 6*1 = 17.

class Solution {
public:
    int depthSumInverse(vector<NestedInteger>& nestedList) {
        int max_depth=0;
        queue<pair<NestedInteger,int>> q;
        for(auto x:nestedList) q.push({x,1});
        while(!q.empty())
        {
            NestedInteger i=q.front().first;
            int depth=q.front().second;
            max_depth=max(max_depth,depth);
            q.pop();
            if(!i.isInteger())
                for(auto x:i.getList()) q.push({x,depth+1});
        }
        
        int sum=0;
        for(auto x:nestedList) q.push({x,1});
        while(!q.empty())
        {
            NestedInteger i=q.front().first;
            int depth=q.front().second;
            q.pop();
            if(i.isInteger()) sum+=(max_depth-depth+1)*i.getInteger();
            else for(auto x:i.getList()) q.push({x,depth+1});
        }
        return sum;
    }
};