leetcode

0 class Solution {

1 public:

2 int mctFromLeafValues(vector<int> &arr) {

3 int res = 0;

4 vector<int> stack = {INT_MAX};

5 for (int n : arr) {

6 while (stack.back() <= n) {

7 int mid = stack.back();

8 stack.pop_back();

9 res += mid * min(stack.back(), n);

10 }

11 stack.push_back(n);

12 }

13

14 for (int i = 2; i < stack.size(); i++)

15 res += stack[i] * stack[i - 1];

16

17 return res;

18 }

19 };