# 339. Nested List Weight Sum

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.
``````

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

``````class Solution {
public:
int depthSum(vector<NestedInteger>& nestedList) {
return helper(nestedList, 1);
}
int helper(vector<NestedInteger>& nl, int depth) {
int res = 0;
for (auto a : nl) {
res += a.isInteger() ? a.getInteger() * depth : helper(a.getList(), depth + 1);
}
return res;
}
};
``````

https://leetcode.com/problems/nested-list-weight-sum/

https://leetcode.com/discuss/94956/2ms-easy-to-understand-java-solution

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