思路1
stack1
负责所有操作,stack2
只是个过客,辅助stack1
代码
//405ms
public class CQueue {
Stack<Integer> stack1;
Stack<Integer> stack2;
public CQueue() {
this.stack1=new Stack<>();
this.stack2=new Stack<>();
}
public void appendTail(int value) {
stack1.add(value);
}
public int deleteHead() {
if(stack1.isEmpty()) return -1;
while(!stack1.isEmpty()&&stack1.size()>1){
stack2.add(stack1.pop());
}
int res=stack1.pop();
while(!stack2.isEmpty()){
stack1.add(stack1.pop());
}
return res;
}
}
思路2
stack1
负责入队列,stack2
负责出队列
代码
//66ms
public class CQueue2 {
//负责入队列
Stack<Integer> stack1;
//负责出队列
Stack<Integer> stack2;
public CQueue2() {
this.stack1 = new Stack<>();
this.stack2 = new Stack<>();
}
public void appendTail(int value) {
stack1.push(value);
}
public int deleteHead() {
if(!stack2.isEmpty()){
return stack2.pop();
}else{
while (!stack1.isEmpty()){
stack2.push(stack1.pop());
}
return stack2.isEmpty()?-1:stack2.pop();
}
}
}