hello,这次我来用C语言和栈和队列相关问题，希望大家多多支持
括号匹配题目：
OJ题目
首先我们不能用数量匹配来进行解答，因为你顺序不一定匹配
解析：
1、左括号入栈2、右括号出栈顶左括号匹配
1.我们只需要找到右括号，判断左括号是否匹配
2、所以遇到左括号就采用进入栈的方式，遇到右括号，出栈顶左括号看是否匹配
typedef char STDataType;
typedef struct Stack
{
STDataType* a;
int top;
int capacity;
}ST;
void StackInit(ST* ps);
void StackDestroy(ST* ps);
void StackPush(ST* ps, STDataType x);
void StackPop(ST* ps);
STDataType StackTop(ST* ps);
int StackSize(ST* ps);
bool StackEmpty(ST* ps);
void StackInit(ST* ps)
{
assert(ps);
ps->a = NULL;
ps->top = 0;//ps->top = -1
ps->capacity = 0;
}
void StackDestroy(ST* ps)
{
assert(ps);
free(ps->a);
ps->a = NULL;
ps->top = ps->capacity = 0;
}
void StackPush(ST* ps, STDataType x)
{
assert(ps);
if (ps->top == ps->capacity)
{
int newCapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
STDataType* tmp = realloc(ps->a, sizeof(STDataType) * newCapacity);
if (tmp == NULL)
{
printf("realloc fail\n");
exit(-1);
}
ps->a = tmp;
ps->capacity = newCapacity;
}
ps->a[ps->top] = x;
ps->top++;
}
void StackPop(ST* ps)
{
assert(ps);
//assert(ps->top > 0);
assert(!StackEmpty(ps));
ps->top--;
}
STDataType StackTop(ST* ps)
{
assert(ps);
//assert(ps->top > 0);
assert(!StackEmpty(ps));
return ps->a[ps->top - 1];
}
int StackSize(ST* ps)
{
assert(ps);
return ps->top;
}
bool StackEmpty(ST* ps)
{
assert(ps);
return ps->top == 0;
}
bool isValid(char* s)
{
ST st;
StackInit(&st);
while(*s)
{
if (*s == '('
|| *s == '{'
|| *s == '[')
{
StackPush(&st, *s);
++s;
}
else
{
if (StackEmpty(&st))
{
StackDestroy(&st);
return false;
}
STDataType top = StackTop(&st);
StackPop(&st);
if ((*s == '}' && top != '{')
|| (*s == ']' && top != '[')
|| (*s == ')' && top != '('))
{
StackDestroy(&st);
return false;
}
else
{
s++;
}
}
}
bool ret = StackEmpty(&st);
StackDestroy(&st);
return ret;
}用队列实现栈
OJ题目
https://leetcode.cn/problems/implement-stack-using-queues/description/
我们知道队列是先进先出，栈是先进后出（后入先出）
1、我们主要保证一个队列是空，然后把这个队列数据存入另外一个队列中，这个时候的队列所出的数据相当于就是栈出的数据。
2、所以插入数据是插到有数据的队列，如果两个都没有数据两个都行。
typedef struct {
Queue q1;
Queue q2;
} MyStack;
/** Initialize your data structure here. */
MyStack* myStackCreate(int maxSize) {
MyStack* pst = (MyStack*)malloc(sizeof(MyStack));
QueueInit(&pst->q1);
QueueInit(&pst->q2);
return pst;
}
/** Push element x onto stack. */
void myStackPush(MyStack* obj, int x) {
//给非空队列进行入队操作
if(QueueEmpty(&obj->q1) != 0)
{
QueuePush(&obj->q1, x);
}
else
{
QueuePush(&obj->q2, x);
}
}
/** Removes the element on top of the stack and returns that element. */
int myStackPop(MyStack* obj) {
//把非空队列的除最后一个元素之外的剩余元素全部入队空队列
Queue* pEmpty = &obj->q1, *pNonEmpty = &obj->q2;
if(QueueEmpty(&obj->q1) != 0)
{
pEmpty = &obj->q2;
pNonEmpty = &obj->q1;
}
while(QueueSize(pNonEmpty) > 1)
{
QueuePush(pEmpty, QueueFront(pNonEmpty));
QueuePop(pNonEmpty);
}
int top = QueueFront(pNonEmpty);
//队尾元素出队
QueuePop(pNonEmpty);
return top;
}
/** Get the top element. */
int myStackTop(MyStack* obj) {
//获取非空队列的队尾元素
Queue* pEmpty = &obj->q1, *pNonEmpty = &obj->q2;
if(QueueEmpty(&obj->q1) != 0)
{
pEmpty = &obj->q2;
pNonEmpty = &obj->q1;
}
return QueueBack(pNonEmpty);
}
/** Returns whether the stack is empty. */
bool myStackEmpty(MyStack* obj) {
return !(QueueEmpty(&obj->q1) | QueueEmpty(&obj->q2));
}
void myStackFree(MyStack* obj) {
QueueDestory(&obj->q1);
QueueDestory(&obj->q2);
free(obj);
}
用栈实现队列
OJ题目https://leetcode.cn/problems/implement-queue-using-stacks/description/
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);
}设计循坏队列
OJ题目https://leetcode.cn/problems/design-circular-queue/description/
typedef struct {
int* queue;
int front;
int rear;
int k
} MyCircularQueue;
/** Initialize your data structure here. Set the size of the queue to be k. */
//创建一个可以存放k个元素的循环队列，实际申请的空间为k + 1
MyCircularQueue* myCircularQueueCreate(int k) {
MyCircularQueue* pcq = (MyCircularQueue*)malloc(sizeof(MyCircularQueue));
pcq->queue = (int*)malloc(sizeof(int)*(k+1));
pcq->front = 0;
pcq->rear = 0;
pcq->k = k;
return pcq;
}
/** Insert an element into the circular queue. Return true if the operation is successful. */
bool myCircularQueueEnQueue(MyCircularQueue* obj, int value) {
//判满
if((obj->rear+1)%(obj->k+1) == obj->front)
{
return false;
}
//队尾入队
obj->queue[obj->rear++] = value;
//如果队尾越界，更新为最小值
if(obj->rear == obj->k+1)
obj->rear = 0;
return true;
}
/** Delete an element from the circular queue. Return true if the operation is successful. */
bool myCircularQueueDeQueue(MyCircularQueue* obj) {
//判空
if(obj->front == obj->rear)
return false;
//队头出队
++obj->front;
//如果队头越界，更新为最小值
if(obj->front == obj->k+1)
obj->front = 0;
return true;
}
/** Get the front item from the queue. */
int myCircularQueueFront(MyCircularQueue* obj) {
if(obj->front == obj->rear)
return -1;
else
return obj->queue[obj->front];
}
/** Get the last item from the queue. */
int myCircularQueueRear(MyCircularQueue* obj) {
if(obj->front == obj->rear)
return -1;
//队尾元素再rear索引的前一个位置，如果rear为0，
//则队尾元素在数组的最后一个位置
if(obj->rear == 0)
return obj->queue[obj->k];
else
return obj->queue[obj->rear-1];
}
/** Checks whether the circular queue is empty or not. */
bool myCircularQueueIsEmpty(MyCircularQueue* obj) {
return obj->front == obj->rear;
}
/** Checks whether the circular queue is full or not. */
bool myCircularQueueIsFull(MyCircularQueue* obj) {
return (obj->rear+1)%(obj->k+1) == obj->front;
}
void myCircularQueueFree(MyCircularQueue* obj) {
free(obj->queue);
free(obj);
}
一些解析都在代码里啦
希望大家多多支持，更喜欢对你有帮助
