682.Baseball Game

Author: recherst

Easy/682.Baseball Game.playground/Contents.swift

@@ -0,0 +1,85 @@
+/**
+ 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 [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.
+ */
+class Solution {
+    func calPoints(_ operations: [String]) -> Int {
+        var numsArr = [Int]()
+        for s in operations {
+            if s == "C" {
+                numsArr.popLast()
+            } else if s == "D" {
+                var newElement: Int = numsArr.last!
+                newElement *= 2
+                numsArr.append(newElement)
+            } else if s == "+" {
+                let last = numsArr.last!
+                let previousLast = numsArr[numsArr.count - 2]
+                let newElement = last + previousLast
+                numsArr.append(newElement)
+            } else {
+                numsArr.append(Int(s)!)
+            }
+        }
+        return numsArr.reduce(0, +)
+    }
+}
+
+let s = Solution()
+let r = s.calPoints(["5","2","C","D","+"])
+print(r)

Easy/682.Baseball Game.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

Easy/682.Baseball Game.playground/playground.xcworkspace/contents.xcworkspacedata

@@ -122,6 +122,7 @@
 118. [Robot Return to Origin](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/657.Robot%20Return%20to%20Origin.playground/Contents.swift)
 119. [Longest Continuous Increasing Subsequence](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/674.Longest%20Continuous%20Increasing%20Subsequence.playground/Contents.swift)
 120. [Valid Palindrome II](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/680.Valid%20Palindrome%20II.playground/Contents.swift)
+121. [Baseball Game](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/682.Baseball%20Game.playground/Contents.swift)
 
 #### Medium