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Merge pull request #1338 from wzqwtt/patch13
添加(0232.用栈实现队列、0225.用队列实现栈)Scala版本
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@ -815,6 +815,89 @@ class MyStack {
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}
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}
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```
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Scala:
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使用两个队列模拟栈:
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```scala
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import scala.collection.mutable
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class MyStack() {
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val queue1 = new mutable.Queue[Int]()
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val queue2 = new mutable.Queue[Int]()
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def push(x: Int) {
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queue1.enqueue(x)
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}
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def pop(): Int = {
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var size = queue1.size
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// 将queue1中的每个元素都移动到queue2
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for (i <- 0 until size - 1) {
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queue2.enqueue(queue1.dequeue())
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}
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var res = queue1.dequeue()
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// 再将queue2中的每个元素都移动到queue1
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while (!queue2.isEmpty) {
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queue1.enqueue(queue2.dequeue())
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}
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res
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}
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def top(): Int = {
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var size = queue1.size
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for (i <- 0 until size - 1) {
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queue2.enqueue(queue1.dequeue())
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}
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var res = queue1.dequeue()
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while (!queue2.isEmpty) {
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queue1.enqueue(queue2.dequeue())
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}
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// 最终还需要把res送进queue1
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queue1.enqueue(res)
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res
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}
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def empty(): Boolean = {
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queue1.isEmpty
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}
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}
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```
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使用一个队列模拟:
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```scala
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import scala.collection.mutable
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class MyStack() {
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val queue = new mutable.Queue[Int]()
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def push(x: Int) {
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queue.enqueue(x)
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}
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def pop(): Int = {
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var size = queue.size
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for (i <- 0 until size - 1) {
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queue.enqueue(queue.head) // 把头添到队列最后
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queue.dequeue() // 再出队
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}
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queue.dequeue()
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}
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def top(): Int = {
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var size = queue.size
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var res = 0
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for (i <- 0 until size) {
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queue.enqueue(queue.head) // 把头添到队列最后
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res = queue.dequeue() // 再出队
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}
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res
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}
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def empty(): Boolean = {
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queue.isEmpty
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}
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}
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```
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-----------------------
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<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>
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@ -495,6 +495,45 @@ void myQueueFree(MyQueue* obj) {
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obj->stackOutTop = 0;
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}
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```
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Scala:
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```scala
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class MyQueue() {
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import scala.collection.mutable
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val stackIn = mutable.Stack[Int]() // 负责出栈
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val stackOut = mutable.Stack[Int]() // 负责入栈
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// 添加元素
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def push(x: Int) {
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stackIn.push(x)
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}
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// 复用代码,如果stackOut为空就把stackIn的所有元素都压入StackOut
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def dumpStackIn(): Unit = {
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if (!stackOut.isEmpty) return
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while (!stackIn.isEmpty) {
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stackOut.push(stackIn.pop())
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}
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}
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// 弹出元素
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def pop(): Int = {
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dumpStackIn()
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stackOut.pop()
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}
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// 获取队头
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def peek(): Int = {
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dumpStackIn()
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val res: Int = stackOut.pop()
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stackOut.push(res)
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res
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}
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// 判断是否为空
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def empty(): Boolean = {
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stackIn.isEmpty && stackOut.isEmpty
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}
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}
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```
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-----------------------
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<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>
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