g0201_0300.s0225_implement_stack_using_queues.MyStack Maven / Gradle / Ivy
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Java Solution for LeetCode algorithm problems, continually updating
package g0201_0300.s0225_implement_stack_using_queues;
// #Easy #Stack #Design #Queue #2022_07_04_Time_0_ms_(100.00%)_Space_41.7_MB_(54.75%)
import java.util.LinkedList;
import java.util.Queue;
public class MyStack {
private Queue queueOne;
private Queue queueTwo;
private int top;
// Initialize your data structure here.
public MyStack() {
queueOne = new LinkedList<>();
queueTwo = new LinkedList<>();
top = 0;
}
// Push element x onto stack.
public void push(int x) {
queueOne.add(x);
top = x;
}
// Removes the element on top of the stack and returns that element.
public int pop() {
while (queueOne.size() > 1) {
int val = queueOne.remove();
top = val;
queueTwo.add(val);
}
int popValue = queueOne.remove();
queueOne.addAll(queueTwo);
queueTwo.clear();
return popValue;
}
// Get the top element.
public int top() {
return top;
}
// Returns whether the stack is empty.
public boolean empty() {
return queueOne.isEmpty();
}
}