LeetCode 2011. Final Value of Variable After Performing Operations

Description

https://leetcode.com/problems/final-value-of-variable-after-performing-operations/

There is a programming language with only four operations and one variable X:

  • ++X and X++ increments the value of the variable X by 1.
  • --X and X-- decrements the value of the variable X by 1.

Initially, the value of X is 0.

Given an array of strings operations containing a list of operations, return the final value of X after performing all the operations.

Example 1:

Input: operations = ["--X","X++","X++"]
Output: 1
Explanation: The operations are performed as follows:
Initially, X = 0.
--X: X is decremented by 1, X =  0 - 1 = -1.
X++: X is incremented by 1, X = -1 + 1 =  0.
X++: X is incremented by 1, X =  0 + 1 =  1.

Example 2:

Input: operations = ["++X","++X","X++"]
Output: 3
Explanation: The operations are performed as follows:
Initially, X = 0.
++X: X is incremented by 1, X = 0 + 1 = 1.
++X: X is incremented by 1, X = 1 + 1 = 2.
X++: X is incremented by 1, X = 2 + 1 = 3.

Example 3:

Input: operations = ["X++","++X","--X","X--"]
Output: 0
Explanation: The operations are performed as follows:
Initially, X = 0.
X++: X is incremented by 1, X = 0 + 1 = 1.
++X: X is incremented by 1, X = 1 + 1 = 2.
--X: X is decremented by 1, X = 2 - 1 = 1.
X--: X is decremented by 1, X = 1 - 1 = 0.

Constraints:

  • 1 <= operations.length <= 100
  • operations[i] will be either "++X""X++""--X", or "X--".

Explanation

Base on the operation to increase the value.

Python Solution

class Solution:
    def finalValueAfterOperations(self, operations: List[str]) -> int:
        x = 0
        
        for operation in operations:
            if operation == '++X' or operation == 'X++':
                x += 1
            elif operation == '--X' or operation == 'X--':
                x -= 1
                
                
        return x
  • Time Complexity: O(N).
  • Space Complexity: O(N).

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