#P9810. Sum of Elements in the Final Sequence
Sum of Elements in the Final Sequence
Sum of Elements in the Final Sequence
You are given a series of k integers \(a_{1 \dots k}\). You need to maintain a sequence by processing these integers one by one in order. The operations are as follows:
- If \(a_i = 0\), remove (pop) the most recently added element from the sequence.
- Otherwise, add (push) \(a_i\) to the sequence.
After processing all \(k\) numbers, calculate and output the sum of the numbers remaining in the sequence.
Example:
| \(a_i\) | Sequence |
|---|---|
| 1 | \(\{1\}\) |
| 3 | \(\{1,3\}\) |
| 5 | \(\{1,3,5\}\) |
| 4 | \(\{1,3,5,4\}\) |
| 0 | \(\{1,3,5\}\) |
| 0 | \(\{1,3\}\) |
| 7 | \(\{1,3,7\}\) |
| 0 | \(\{1,3\}\) |
| 0 | \(\{1\}\) |
| 6 | \(\{1,6\}\) |
The final sum is \(1 + 6 = 7\).
inputFormat
The first line contains a single integer \(k\), the number of operations.
The second line contains \(k\) space-separated integers \(a_1, a_2, \dots, a_k\).
outputFormat
Output a single integer, the sum of the numbers remaining in the sequence after performing all operations.
sample
10
1 3 5 4 0 0 7 0 0 67