14.用栈实现队列

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232. 用栈实现队列 - 力扣（LeetCode）

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/*
解题思路：
此题可以用两个栈实现，一个栈进行入队操作，另一个栈进行出队操作
出队操作： 当出队的栈不为空是，直接进行出栈操作，如果为空，需要把入队的栈元素全部导入到出队的栈，然后再进行出栈操作
*/

 

typedef struct {//入队栈Stack pushST;//出队栈Stack popST;
} MyQueue;/** Initialize your data structure here. */
MyQueue* myQueueCreate(int maxSize) {MyQueue* pqueue = (MyQueue*)malloc(sizeof(MyQueue));StackInit(&pqueue->pushST, maxSize);StackInit(&pqueue->popST, maxSize);return pqueue;
}/** Push element x to the back of queue. */
void myQueuePush(MyQueue* obj, int x) {//入队栈进行入栈操作StackPush(&obj->pushST, x);
}/** Removes the element from in front of queue and returns that element. */
int myQueuePop(MyQueue* obj) {//如果出队栈为空，导入入队栈的元素if(StackEmpty(&obj->popST) == 0){while(StackEmpty(&obj->pushST) != 0){StackPush(&obj->popST, StackTop(&obj->pushST));StackPop(&obj->pushST);}}int front = StackTop(&obj->popST);//出队栈进行出队操作StackPop(&obj->popST);return front;
}/** Get the front element. */
int myQueuePeek(MyQueue* obj) {//类似于出队操作if(StackEmpty(&obj->popST) == 0){while(StackEmpty(&obj->pushST) != 0){StackPush(&obj->popST, StackTop(&obj->pushST));StackPop(&obj->pushST);}}return StackTop(&obj->popST);
}/** Returns whether the queue is empty. */
bool myQueueEmpty(MyQueue* obj) {return StackEmpty(&obj->pushST) == 0&&  StackEmpty(&obj->popST) == 0;
}void myQueueFree(MyQueue* obj) {StackDestroy(&obj->pushST);StackDestroy(&obj->popST);free(obj);
}