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LeetCode232.java
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81 lines (71 loc) · 1.63 KB
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package stack;
import java.util.Stack;
/**
* Description:
* leetcode232
* @author elijahliu
* @Note Talk is cheap,just show me ur code.- -!
* ProjectName:EAlgorithm
* PackageName: stack
* Date: 2020/8/14 16:55
*/
public class LeetCode232 {
Stack<Integer> stack1;
Stack<Integer> stack2;
/**
* Initialize your data structure here.
*/
public LeetCode232() {
stack1 = new Stack<>();
stack2 = new Stack<>();
}
/**
* Push element x to the back of queue.
*/
public void push(int x) {
stack1.push(x);
}
/**
* Removes the element from in front of queue and returns that element.
*/
public int pop() {
if (stack2.isEmpty()) {
if (stack1.isEmpty()) {
return -1;
} else {
while (!stack1.isEmpty()) {
stack2.push(stack1.pop());
}
return stack2.pop();
}
} else {
return stack2.pop();
}
}
/**
* Get the front element.
*/
public int peek() {
if (stack2.isEmpty()) {
if (stack1.isEmpty()) {
return -1;
} else {
while (!stack1.isEmpty()) {
stack2.push(stack1.pop());
}
return stack2.peek();
}
} else {
return stack2.peek();
}
}
/**
* Returns whether the queue is empty.
*/
public boolean empty() {
if (stack2.isEmpty() && stack1.isEmpty()) {
return true;
}
return false;
}
}