[LeetCode] Baseball Game

1.문제

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.

야구게임의 진행상황을 기록한 operation이라는 배열이 주어질때 주어진 규칙에따라 야구게임 점수를 계산하는 문제이다.

Example 1

Input: ops = ["5","2","C","D","+"]
Output: 30
Explanation:
"5" - Add 5 to the record, record is now [5].
"2" - Add 2 to the record, record is now [5, 2].
"C" - Invalidate and remove the previous score, record is now [5].
"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 [5].
"-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 [1].
"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.

2.풀이

1. operations의 조건에 따라서 record 배열에 점수를 기록한다.
2. record 배열의 값들을 더해서 리턴한다.

/**
 * @param {string[]} operations
 * @return {number}
 */
const calPoints = function (operations) {
  const record = [];
  let sum = 0;

  // operations 에 따라 조건을 체크해서 record를 기록한다.
  for (let i = 0; i < operations.length; i++) {
    if (operations[i] === "+") {
      record.push(record[record.length - 1] + record[record.length - 2]);
    } else if (operations[i] === "C") {
      record.pop();
    } else if (operations[i] === "D") {
      record.push(record[record.length - 1] * 2);
    } else {
      record.push(parseInt(operations[i]));
    }
  }

  // record 배열의 길이가 0보다 크면 record 배열 숫자들의 합을 리턴
  if (record.length > 0) {
    for (let i = 0; i < record.length; i++) {
      sum += record[i];
    }
  }

  return sum;
};

3.결과