Leetcode 1497 Solution

This article provides solution to leetcode question 1497 (design-a-stack-with-increment-operation).
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https://leetcode.com/problems/design-a-stack-with-increment-operation

Solution

class CustomStack:

    def __init__(self, maxSize: int):
        self.maxSize = maxSize
        self.vals = []
        self.inc_vals = collections.defaultdict(int)

    def push(self, x: int) -> None:
        if len(self.vals) == self.maxSize:
            return
        
        self.vals.append(x)

    def pop(self) -> int:
        if not self.vals:
            return -1
        
        index = len(self.vals) - 1
        
        if index in self.inc_vals:
            inc = self.inc_vals[index]
            del self.inc_vals[index]
            
            if index > 0:
                self.inc_vals[index - 1] += inc
        else:
            inc = 0
            
        return self.vals.pop() + inc

    def increment(self, k: int, val: int) -> None:
        k = min(k, len(self.vals))
        self.inc_vals[k - 1] += val


# Your CustomStack object will be instantiated and called as such:
# obj = CustomStack(maxSize)
# obj.push(x)
# param_2 = obj.pop()
# obj.increment(k,val)