## Algorithm

Problem Name: 682. Baseball Game

You are keeping the scores for a baseball game with strange rules. At the beginning of the game, you start with an empty record.

You are given a list of strings `operations`, where `operations[i]` is the `ith` operation you must apply to the record and is one of the following:

• An integer `x`.
• Record a new score of `x`.
• `'+'`.
• Record a new score that is the sum of the previous two scores.
• `'D'`.
• Record a new score that is the double of the previous score.
• `'C'`.
• Invalidate the previous score, removing it from the record.

Return the sum of all the scores on the record after applying all the operations.

The test cases are generated such that the answer and all intermediate calculations fit in a 32-bit integer and that all operations are valid.

Example 1:

```Input: ops = ["5","2","C","D","+"]
Output: 30
Explanation:
"5" - Add 5 to the record, record is now .
"2" - Add 2 to the record, record is now [5, 2].
"C" - Invalidate and remove the previous score, record is now .
"D" - Add 2 * 5 = 10 to the record, record is now [5, 10].
"+" - Add 5 + 10 = 15 to the record, record is now [5, 10, 15].
The total sum is 5 + 10 + 15 = 30.
```

Example 2:

```Input: ops = ["5","-2","4","C","D","9","+","+"]
Output: 27
Explanation:
"5" - Add 5 to the record, record is now .
"-2" - Add -2 to the record, record is now [5, -2].
"4" - Add 4 to the record, record is now [5, -2, 4].
"C" - Invalidate and remove the previous score, record is now [5, -2].
"D" - Add 2 * -2 = -4 to the record, record is now [5, -2, -4].
"9" - Add 9 to the record, record is now [5, -2, -4, 9].
"+" - Add -4 + 9 = 5 to the record, record is now [5, -2, -4, 9, 5].
"+" - Add 9 + 5 = 14 to the record, record is now [5, -2, -4, 9, 5, 14].
The total sum is 5 + -2 + -4 + 9 + 5 + 14 = 27.
```

Example 3:

```Input: ops = ["1","C"]
Output: 0
Explanation:
"1" - Add 1 to the record, record is now .
"C" - Invalidate and remove the previous score, record is now [].
Since the record is empty, the total sum is 0.
```

Constraints:

• `1 <= operations.length <= 1000`
• `operations[i]` is `"C"`, `"D"`, `"+"`, or a string representing an integer in the range `[-3 * 104, 3 * 104]`.
• For operation `"+"`, there will always be at least two previous scores on the record.
• For operations `"C"` and `"D"`, there will always be at least one previous score on the record.

## Code Examples

### #1 Code Example with Java Programming

```Code - Java Programming```

``````
class Solution {
public int calPoints(String[] ops) {
Stack stack = new Stack<>();
int totalScore = 0;
for (String op : ops) {
if (op.equals("D")) {
int newScore = 2 * stack.peek();
totalScore += newScore;
stack.push(newScore);
} else if (op.equals("C")) {
totalScore -= stack.pop();
} else if (op.equals("+")) {
int scoreTwo = stack.pop();
int newScore = scoreTwo + stack.peek();
stack.push(scoreTwo);
stack.push(newScore);
totalScore += newScore;
} else {
stack.push(Integer.parseInt(op));
totalScore += Integer.parseInt(op);
}
}
}
}
``````
Copy The Code &

Input

cmd
ops = ["5","2","C","D","+"]

Output

cmd
30

### #2 Code Example with Javascript Programming

```Code - Javascript Programming```

``````
const calPoints = function(ops) {
const opArr = ["C", "D", "+"];
const arr = [];
ops.forEach((el, idx) => {
const item = {
value: 0,
valid: true
};
switch (el) {
case "C":
findValid(arr, idx, 1).forEach(el => {
el.value = 0;
el.valid = false;
});
item.valid = false;
break;
case "D":
item.value = findValid(arr, idx, 1).value * 2;
break;
case "+":
item.value = findValid(arr, idx, 2).reduce(
(ac, ele) => ac + ele.value,
0
);
break;
default:
item.value = +el;
break;
}
arr.push(item);
});
return arr.reduce((ac, el) => ac + el.value, 0);
};

function findValid(arr, idx, backStep) {
const res = [];
while (backStep > 0 && idx - 1 >= 0) {
if (arr[idx - 1].valid === true) {
backStep -= 1;
res.push(arr[idx - 1]);
}
idx -= 1;
}
return res;
}

console.log(calPoints(["5", "2", "C", "D", "+"]));
console.log(calPoints(["5", "-2", "4", "C", "D", "9", "+", "+"]));
``````
Copy The Code &

Input

cmd
ops = ["5","2","C","D","+"]

Output

cmd
30

### #3 Code Example with Python Programming

```Code - Python Programming```

``````
class Solution:
def calPoints(self, ops: List[str]) -> int:
arr = []
for op in ops:
#print(arr)
if op.isdigit() or op == '-':
arr.append(int(op))
elif op == 'C' and arr:
arr.pop()
elif op == 'D' and arr:
arr.append(arr[-1] * 2)
elif len(arr) >= 2:
arr.append(arr[-1] + arr[-2])
#print(arr)
return sum(arr)
``````
Copy The Code &

Input

cmd
ops = ["5","-2","4","C","D","9","+","+"]

Output

cmd
27

### #4 Code Example with C# Programming

```Code - C# Programming```

``````
namespace LeetCode
{
public class _0682_BaseballGame
{
public int CalPoints(string[] ops)
{
var roundPoints = new int[ops.Length];
var index = 0;

foreach (var op in ops)
{
if (op == "C")
index--;
else if (op == "D")
{
roundPoints[index] = roundPoints[index - 1] * 2;
index++;
}
else if (op == "+")
{
roundPoints[index] = roundPoints[index - 1] + roundPoints[index - 2];
index++;
}
else
roundPoints[index++] = int.Parse(op);
}

var sum = 0;
for (int i = 0; i < index; i++)
sum += roundPoints[i];

return sum;
}
}
}
``````
Copy The Code &

Input

cmd
ops = ["5","-2","4","C","D","9","+","+"]

Output

cmd
27