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[leetcode stack and queue -- minimum stack] 155. Minimum stack

2022-07-22 16:37:00 【alone_ yue】

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Leetcode 155. Smallest stack
- 1. Problem description
- 2. Solution

Leetcode 155. Smallest stack

1. Problem description

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2. Solution

Auxiliary stack min_stack and stack Store the same number of elements , Deposit is ,stack The corresponding element in push Minimum value after entering

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class MinStack {
    

    private LinkedList<Integer> stack;
    private LinkedList<Integer> min_stack;

    public MinStack() {
    
        stack = new LinkedList<>();
        min_stack = new LinkedList<>();
    }
    
    public void push(int val) {
    
        stack.addLast(val);
        if(min_stack.size()==0){
    
            min_stack.addLast(val);
        }else{
    
            min_stack.addLast(Math.min(val, min_stack.getLast()));
        }
    }
    
    public void pop() {
    
        stack.removeLast();
        min_stack.removeLast();
    }
    
    public int top() {
    
        return stack.getLast();
    }
    
    public int getMin() {
    
        return min_stack.getLast();
    }
}

/** * 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(); */