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155_MinStack.java
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155_MinStack.java
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class MinStack {
Stack<Integer> stack;
Stack<Integer> minStack;
public MinStack(){
stack = new Stack<>();
minStack = new Stack<>();
}
public void push(int val) {
stack.push(val);
if(minStack.isEmpty() || minStack.peek() >= val){
minStack.push(val);
}
}
public void pop() {
if(stack.isEmpty()){
return;
}
if(minStack.peek().equals(stack.peek())){
minStack.pop();
}
stack.pop();
}
public int top() {
if(stack.isEmpty()){
return -1;
}
return stack.peek();
}
public int getMin() {
if(minStack.isEmpty()){
return -1;
}
return minStack.peek();
}
}
/**
* 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();
*/