(C语言)用栈实现序列

请你仅使用两个栈实现先入先出队列。队列应当支持一般队列支持的所有操作(push、pop、peek、empty):

实现 MyQueue 类:

void push(int x) 将元素 x 推到队列的末尾
int pop() 从队列的开头移除并返回元素
int peek() 返回队列开头的元素
boolean empty() 如果队列为空,返回 true ;否则,返回 false

来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/implement-queue-using-stacks
著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。

代码是力扣官方给出的代码

//首先是创建栈的过程
typedef struct {
    int* stk;
    int stkSize;
    int stkCapacity;
} Stack;

Stack* stackCreate(int cpacity) {
    Stack* ret = malloc(sizeof(Stack));
    ret->stk = malloc(sizeof(int) * cpacity);
    ret->stkSize = 0;
    ret->stkCapacity = cpacity;
    return ret;
}

void stackPush(Stack* obj, int x) {
    obj->stk[obj->stkSize++] = x;
}

void stackPop(Stack* obj) {
    obj->stkSize--;
}

int stackTop(Stack* obj) {
    return obj->stk[obj->stkSize - 1];
}

bool stackEmpty(Stack* obj) {
    return obj->stkSize == 0;
}

void stackFree(Stack* obj) {
    free(obj->stk);
}


//开始创建队列
typedef struct {
    Stack* inStack;
    Stack* outStack;
} MyQueue;

MyQueue* myQueueCreate() {
    MyQueue* ret = malloc(sizeof(MyQueue));
    ret->inStack = stackCreate(100);
    ret->outStack = stackCreate(100);
    return ret;
}

void in2out(MyQueue* obj) {
    while (!stackEmpty(obj->inStack)) {
        stackPush(obj->outStack, stackTop(obj->inStack));
        stackPop(obj->inStack);
    }
}

void myQueuePush(MyQueue* obj, int x) {
    stackPush(obj->inStack, x);
}

int myQueuePop(MyQueue* obj) {
    if (stackEmpty(obj->outStack)) {
        in2out(obj);
    }
    int x = stackTop(obj->outStack);
    stackPop(obj->outStack);
    return x;
}

int myQueuePeek(MyQueue* obj) {
    if (stackEmpty(obj->outStack)) {
        in2out(obj);
    }
    return stackTop(obj->outStack);
}

bool myQueueEmpty(MyQueue* obj) {
    return stackEmpty(obj->inStack) && stackEmpty(obj->outStack);
}

void myQueueFree(MyQueue* obj) {
    stackFree(obj->inStack);
    stackFree(obj->outStack);
}

上一篇:232. Implement Queue using Stacks


下一篇:List集合