_155. Min Stack.md

155. Min Stack

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First completed : June 16, 2024

Last updated : July 01, 2024

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Related Topics : Stack, Design

Acceptance Rate : 55.24 %

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Solutions

• m155.py

Python

m155.py

# Prompt: All operations must be O(1)

class MinStack {
    private Stack<int[]> vals;
    public MinStack() {
        this.vals = new Stack<>();
    }
    
    public void push(int val) {
        int newMin = (vals.size() > 0 && vals.peek()[1] < val) ? vals.peek()[1] : val;
        vals.push(new int[] {val, newMin});
    }
    
    public void pop() {
        vals.pop();
    }
    
    public int top() {
        return vals.peek()[0];
    }
    
    public int getMin() {
        return vals.peek()[1];
    }
}

/**
 * Your MinStack object will be instantiated and called as such:
 * MinStack obj = new MinStack();
 * obj.push(val);
 * obj.pop();
 * int param_3 = obj.top();
 * int param_4 = obj.getMin();
 */