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Stack225.java
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99 lines (87 loc) · 2.58 KB
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package stack;
import java.util.ArrayDeque;
import java.util.Queue;
public class Stack225 {
static class MyStack2 {
Queue<Integer> queue;
int size;
/** Initialize your data structure here. */
public MyStack2() {
queue = new ArrayDeque();
size = 0;
}
/** Push element x onto stack. */
public void push(int x) {
size = queue.size();
queue.add(x);
while (size > 0) {
queue.add(queue.poll());
size--;
}
}
/** Removes the element on top of the stack and returns that element. */
public int pop() {
return queue.poll();
}
/** Get the top element. */
public int top() {
return queue.peek();
}
/** Returns whether the stack is empty. */
public boolean empty() {
return queue.isEmpty();
}
}
static class MyStack {
Queue<Integer> queue1, queue2;
/** Initialize your data structure here. */
public MyStack() {
queue1 = new ArrayDeque();
queue2 = new ArrayDeque();
}
/** Push element x onto stack. */
public void push(int x) {
if (!queue1.isEmpty()) {
queue1.add(x);
} else {
queue2.add(x);
}
}
/** Removes the element on top of the stack and returns that element. */
public int pop() {
if (queue1.isEmpty()) {
while (queue2.size() > 1) {
queue1.add(queue2.poll());
}
return queue2.poll();
} else {
while (queue1.size() > 1) {
queue2.add(queue1.poll());
}
return queue1.poll();
}
}
/** Get the top element. */
public int top() {
int result;
if (queue1.isEmpty()) {
while (queue2.size() > 1) {
queue1.add(queue2.poll());
}
result = queue2.poll();
queue1.add(result);
} else {
while (queue1.size() > 1) {
queue2.add(queue1.poll());
}
result = queue1.poll();
queue2.add(result);
}
return result;
}
/** Returns whether the stack is empty. */
public boolean empty() {
return queue1.isEmpty() && queue2.isEmpty();
}
}
}