update: solution for baseball game

Author: ashokdey

src/_DataStructures_/Stack/baseball-game/index.js

@@ -0,0 +1,101 @@
+/**
+ 
+You're now a baseball game point recorder.
+
+Given a list of strings, each string can be one of the 4 following types:
+
+Integer (one round's score): Directly represents the number of points you get in this round.
+"+" (one round's score): Represents that the points you get in this round are the sum of the last two valid round's points.
+"D" (one round's score): Represents that the points you get in this round are the doubled data of the last valid round's points.
+"C" (an operation, which isn't a round's score): Represents the last valid round's points you get were invalid and should be removed.
+Each round's operation is permanent and could have an impact on the round before and the round after.
+
+You need to return the sum of the points you could get in all the rounds.
+
+*/
+
+const Stack = require('../index');
+
+// The given solution is on O(n)
+
+function sumOfPoints(arr) {
+  const pointsTracker = new Stack();
+  let sum = 0;
+
+  if (!Array.isArray(arr)) {
+    throw new Error('Invalid Argument!');
+  }
+  // Track the value of `sum` accordingly
+  for (let el of arr) {
+    // console.log('data : ', pointsTracker.data);
+    // console.log('sum : ', sum);
+
+    if (el === 'C') {
+      // pop if the value is `C`
+      const top = pointsTracker.pop();
+      if (top) {
+        sum -= top;
+      }
+    } else if (el === 'D') {
+      // Double the top id the value is 'D'
+      const top = pointsTracker.peek();
+      sum += top * 2;
+      pointsTracker.push(top * 2);
+    } else if (el === '+') {
+      const top = pointsTracker.pop();
+      const secondTop = pointsTracker.peek();
+
+      const result = top + secondTop;
+      sum += result;
+
+      pointsTracker.push(top);
+      pointsTracker.push(result);
+    } else {
+      // push to the Stack if the value is integer
+      sum += parseInt(el);
+      pointsTracker.push(parseInt(el));
+    }
+  }
+  return sum;
+}
+
+/**
+ * Let's Try it out
+ 
+console.log(sumOfPoints(['5', '2', 'C', 'D', '+']));
+console.log(sumOfPoints(['5', '-2', '4', 'C', 'D', '9', '+', '+']));
+ */
+
+/** 
+ 
+Input: ["5","2","C","D","+"]
+Output: 30
+
+Explanation: 
+
+Round 1: You could get 5 points. The sum is: 5.
+Round 2: You could get 2 points. The sum is: 7.
+Operation 1: The round 2's data was invalid. The sum is: 5.  
+Round 3: You could get 10 points (the round 2's data has been removed). The sum is: 15.
+Round 4: You could get 5 + 10 = 15 points. The sum is: 30.
+Example 2:
+Input: ["5","-2","4","C","D","9","+","+"]
+Output: 27
+
+Explanation: 
+
+Round 1: You could get 5 points. The sum is: 5.
+Round 2: You could get -2 points. The sum is: 3.
+Round 3: You could get 4 points. The sum is: 7.
+Operation 1: The round 3's data is invalid. The sum is: 3.  
+Round 4: You could get -4 points (the round 3's data has been removed). The sum is: -1.
+Round 5: You could get 9 points. The sum is: 8.
+Round 6: You could get -4 + 9 = 5 points. The sum is 13.
+Round 7: You could get 9 + 5 = 14 points. The sum is 27.
+
+Note:
+
+The size of the input list will be between 1 and 1000.
+Every integer represented in the list will be between -30000 and 30000.
+
+*/