目录
一、括号匹配问题
20. 有效的括号 - 力扣（LeetCode）
思路：
完整版C语言代码：
typedef char STDataType;
typedef struct Stack
{
STDataType* a;
int top;
int capacity;
}ST;
void STInit(ST* pst)
{
assert(pst);
pst->a = NULL;
pst->top = 0;
pst->capacity = 0;
}
void STDestroy(ST* pst)
{
assert(pst);
free(pst->a);
pst->a = NULL;
pst->top = 0;
pst->capacity = 0;
}
void STPush(ST* pst,STDataType x)
{
if (pst->top == pst->capacity) {
int newCapacity = pst->capacity == 0 ? 4 :pst-> capacity * 2;
STDataType* tmp = (STDataType*)realloc(pst->a, newCapacity * sizeof(STDataType));
if (tmp == NULL) {
perror("realloc fail");
return;
}
pst->a = tmp;
pst->capacity = newCapacity;
}
pst->a[pst->top] = x;
pst->top++;
}
bool STEmpty(ST* pst)
{
assert(pst);
return pst->top == 0;
}
void STPop(ST* pst)
{
assert(pst);
assert(!STEmpty(pst));
pst->top--;
}
STDataType STTop(ST* pst)
{
assert(pst);
assert(!STEmpty(pst));
return pst->a[pst->top - 1];
}
int STSize(ST* pst)
{
assert(pst);
return pst->top;
}
//------以下为OJ提供-------
bool isValid(char* s) {
ST st;
STInit(&st);
while (*s) {
if (*s == '(' || *s == '[' || *s == '{') {
STPush(&st, *s);
}
else {
if (STEmpty(&st)) {
STDestroy(&st);
return false;
}
char top = STTop(&st);
STPop(&st);
if ((top != '(' && *s == ')') ||
(top != '{' && *s == '}') ||
(top != '[' && *s == ']')) {
STDestroy(&st);
return false;
}
}
s++;
}
bool ret = STEmpty(&st);
STDestroy(&st);
return ret;
}讲解：
二、用队列实现栈
225. 用队列实现栈 - 力扣（LeetCode）
思路：
完整版C语言代码：
typedef int QDataType;
typedef struct QueueNode
{
struct QueueNode* next;
QDataType data;
}QNode;
typedef struct Queue
{
QNode* phead;
QNode* ptail;
int size;
}Queue;
void QueueInit(Queue* pq)
{
assert(pq);
pq->phead = NULL;
pq->ptail = NULL;
pq->size = 0;
}
void QueueDestroy(Queue* pq)
{
assert(pq);
QNode* cur = pq->phead;
while (cur) {
QNode* next = cur->next;
free(cur);
cur = next;
}
pq->phead = pq->ptail = NULL;
pq->size = 0;
}
void QueuePush(Queue* pq, QDataType x)
{
assert(pq);
QNode* newnode = (QNode*)malloc(sizeof(QNode));
if (newnode == NULL) {
perror("mallloc fail\n");
return;
}
newnode->data = x;
newnode->next = NULL;
if (pq->ptail == NULL) {
assert(pq->phead == NULL);
pq->phead = pq->ptail = newnode;
}
else {
pq->ptail->next = newnode;
pq->ptail = newnode;
}
pq->size++;
}
bool QueueEmpty(Queue* pq)
{
assert(pq);
return pq->size == 0;
}
void QueuePop(Queue* pq)
{
assert(pq);
assert(!QueueEmpty(pq));
if (pq->phead->next == NULL) {
free(pq->phead);
pq->phead = pq->ptail = NULL;
}
else {
QNode* next = pq->phead->next;
free(pq->phead);
pq->phead = next;
}
pq->size--;
}
QDataType QueueFront(Queue* pq)
{
assert(pq);
assert(!QueueEmpty(pq));
return pq->phead->data;
}
QDataType QueueBack(Queue* pq)
{
assert(pq);
assert(!QueueEmpty(pq));
return pq->ptail->data;
}
int QueueSize(Queue* pq)
{
assert(pq);
return pq->size;
}
//------以下为OJ提供-------
typedef struct {
Queue q1;
Queue q2;
} MyStack;
MyStack* myStackCreate() {
MyStack* obj = (MyStack*)malloc(sizeof(MyStack));
if (obj == NULL) {
perror("malloc fail");
return NULL;
}
QueueInit(&obj->q1);
QueueInit(&obj->q2);
return obj;
}
void myStackPush(MyStack* obj, int x) {
if (!QueueEmpty(&obj->q1)) {
QueuePush(&obj->q1, x);
}
else {
QueuePush(&obj->q2, x);
}
}
int myStackPop(MyStack* obj) {
Queue* pEmptyQ = &obj->q1;
Queue* pNonEmptyQ = &obj->q2;
if (!QueueEmpty(&obj->q1)) {
pEmptyQ = &obj->q2;
pNonEmptyQ = &obj->q1;
}
while (QueueSize(pNonEmptyQ) > 1) {
QueuePush(pEmptyQ, QueueFront(pNonEmptyQ));
QueuePop(pNonEmptyQ);
}
int top = QueueFront(pNonEmptyQ);
QueuePop(pNonEmptyQ);
return top;
}
int myStackTop(MyStack* obj) {
if (!QueueEmpty(&obj->q1)) {
return QueueBack(&obj->q1);
}
else {
return QueueBack(&obj->q2);
}
}
bool myStackEmpty(MyStack* obj) {
return QueueEmpty(&obj->q1) &&
QueueEmpty(&obj->q2);
}
void myStackFree(MyStack* obj) {
QueueDestroy(&obj->q1);
QueueDestroy(&obj->q2);
free(obj);
}讲解：
三、用栈实现队列
232. 用栈实现队列 - 力扣（LeetCode）
思路：
完整版C语言代码：
typedef int STDataType;
typedef struct Stack
{
STDataType* a;
int top;
int capacity;
}ST;
void STInit(ST* pst)
{
assert(pst);
pst->a = NULL;
pst->top = 0;
pst->capacity = 0;
}
void STDestroy(ST* pst)
{
assert(pst);
free(pst->a);
pst->a = NULL;
pst->top = 0;
pst->capacity = 0;
}
void STPush(ST* pst, STDataType x)
{
if (pst->top == pst->capacity) {
int newCapacity = pst->capacity == 0 ? 4 : pst->capacity * 2;
STDataType* tmp = (STDataType*)realloc(pst->a, newCapacity * sizeof(STDataType));
if (tmp == NULL) {
perror("realloc fail");
return;
}
pst->a = tmp;
pst->capacity = newCapacity;
}
pst->a[pst->top] = x;
pst->top++;
}
bool STEmpty(ST* pst)
{
assert(pst);
return pst->top == 0;
}
void STPop(ST* pst)
{
assert(pst);
assert(!STEmpty(pst));
pst->top--;
}
STDataType STTop(ST* pst)
{
assert(pst);
assert(!STEmpty(pst));
return pst->a[pst->top - 1];
}
int STSize(ST* pst)
{
assert(pst);
return pst->top;
}
//------以下为OJ提供-------
typedef struct {
ST pushst;
ST popst;
} MyQueue;
MyQueue* myQueueCreate() {
MyQueue* obj = (MyQueue*)malloc(sizeof(MyQueue));
if (obj == NULL) {
perror("malloc fail");
return 0;
}
STInit(&obj->pushst);
STInit(&obj->popst);
return obj;
}
void myQueuePush(MyQueue* obj, int x) {
STPush(&obj->pushst, x);
}
int myQueuePop(MyQueue* obj) {
int front = myQueuePeek(obj);
STPop(&obj->popst);
return front;
}
int myQueuePeek(MyQueue* obj) {
if (STEmpty(&obj->popst)) {
while (!STEmpty(&obj->pushst)) {
STPush(&obj->popst, STTop(&obj->pushst));
STPop(&obj->pushst);
}
}
return STTop(&obj->popst);
}
bool myQueueEmpty(MyQueue* obj) {
return STEmpty(&obj->pushst) && STEmpty(&obj->popst);
}
void myQueueFree(MyQueue* obj) {
STDestroy(&obj->pushst);
STDestroy(&obj->popst);
free(obj);
}讲解：
四、 设计循环队列
622. 设计循环队列
思路：
完整版C语言代码：
typedef struct {
int front;
int rear;
int k;
int* a;
} MyCircularQueue;
MyCircularQueue* myCircularQueueCreate(int k) {
MyCircularQueue* obj = (MyCircularQueue*)malloc(sizeof(MyCircularQueue));
obj->a = (int*)malloc((k + 1) * sizeof(int));
obj->k = k;
obj->front = obj->rear = 0;
return obj;
}
bool myCircularQueueIsEmpty(MyCircularQueue* obj) {
return obj->front == obj->rear;
}
bool myCircularQueueIsFull(MyCircularQueue* obj) {
return (obj->rear + 1) % (obj->k + 1) == obj->front;
}
bool myCircularQueueEnQueue(MyCircularQueue* obj, int value) {
if (myCircularQueueIsFull(obj)) {
return false;
}
obj->a[obj->rear] = value;
obj->rear++;
obj->rear %= (obj->k + 1);
return true;
}
bool myCircularQueueDeQueue(MyCircularQueue* obj) {
if (myCircularQueueIsEmpty(obj)) {
return false;
}
obj->front++;
obj->front %= (obj->k + 1);
return true;
}
int myCircularQueueFront(MyCircularQueue* obj) {
if (myCircularQueueIsEmpty(obj)) {
return -1;
}
return obj->a[obj->front];
}
int myCircularQueueRear(MyCircularQueue* obj) {
if (myCircularQueueIsEmpty(obj)) {
return -1;
}
return obj->a[(obj->rear + obj->k) % (obj->k + 1)];
}
void myCircularQueueFree(MyCircularQueue* obj) {
free(obj->a);
free(obj);
}
