栈与队列相关面试题

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设计包含min函数的栈

#include <iostream>#include <vector>#include <assert.h>using namespace std; template <typename T> class CStackWithMin{public:    CStackWithMin(void) {}    virtual ~CStackWithMin(void) {}     T& top(void);    const T& top(void) const;     void push(const T& value);    void pop(void);     const T& min(void) const;private:    vector<T> m_data;    vector<size_t> m_minIndex;}; template <typename T> T& CStackWithMin<T>::top(void){    return m_data.back();} template <typename T> const T& CStackWithMin<T>::top(void) const{    return m_data.back();}template <typename T> void CStackWithMin<T>::push(const T& value){    m_data.push_back(value);     if(m_minIndex.size() == 0) {        m_minIndex.push_back(0);    } else {        if (value < m_data[m_minIndex.back()]) {            m_minIndex.push_back(m_data.size()-1);        } else {            m_minIndex.push_back(m_minIndex.back());        }    }} template <typename T> void CStackWithMin<T>::pop(){    m_data.pop_back();     m_minIndex.pop_back();} template <typename T> const T& CStackWithMin<T>::min() const{    assert(m_data.size() > 0);    assert(m_minIndex.size() > 0);     return m_data[m_minIndex.back()];}

堆栈模拟队列

/* START:: code for queue */typedef struct queue {        stack_t s1[1]; /* for in queue */        stack_t s2[1]; /* for out queue */} queue_t;void init_queue(queue_t *q){        init_stack(q->s1);        init_stack(q->s2);}void in_queue(queue_t *q, int new){        push(q->s1, new);}int out_queue(queue_t *q){        if (!empty(q->s2))                return pop(q->s2);        while (!empty(q->s1)) {                int tmp = pop(q->s1);                push(q->s2, tmp);        }        return pop(q->s2);}int q_empty(queue_t *q){        return empty(q->s1) && empty(q->s2);}/* END:: code for queue */

环形队列

/* START:: code for queue */#define QUEUE_SIZE 32int out_queue_err = 0;typedef struct {        int data[QUEUE_SIZE];        int inpos;        int outpos;} queue_t;void init_queue(queue_t *q){        memset(q->data, 0, sizeof(int) * QUEUE_SIZE);        q->inpos = q->outpos = 0;}int in_queue(queue_t *q, int new){        int pos = (q->inpos + 1) % QUEUE_SIZE;         if (pos == q->outpos)                return -1;        q->data[q->inpos] = new;        q->inpos = pos;        return 0;}int out_queue(queue_t *q) {        int ret;        if (q->outpos == q->inpos) {                out_queue_err = -1;                return -1;        }        ret = q->data[q->outpos];        q->outpos = (q->outpos + 1) % QUEUE_SIZE;        return ret;}int empty(queue_t *q){        return q->inpos == q->outpos;}/* END:: code for queue */

队列模拟堆栈

/* START:: code for stack */typedef struct stack {        queue_t q[2];        int in;} stack_t;void init_stack(stack_t *s){        init_queue(s->q);        init_queue(s->q + 1);        s->in = 0;}int push(stack_t *s, int data){        return in_queue(s->q + s->in, data);}int pop(stack_t *s) {        int ret, other;        if (s->in == 0)                other = 1;        else                 other = 0;        ret = out_queue(s->q + s->in);        while (!empty(s->q + s->in)) {                in_queue(s->q + other, ret);                ret = out_queue(s->q + s->in);        }        s->in = other;        return ret;}

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