面试题之堆栈队列系列一：设计包含min函数的栈

编译环境

前言

正文

【题目】

【例子】

【分析】

【代码】

#ifndef STACK_HPP

#define  STACK_SIZE 20

typedef struct {
int data[STACK_SIZE];
int top;
int min;
}Stack;

void init( Stack *s );
void push( Stack *s, int val );
int pop( Stack *s );
bool full( Stack *s );
bool empty( Stack *s );
int min( Stack *s );

#endif

#include <iostream>
#include <cstdio>
#include <cstring>
#include "stack.hpp"

Stack assist;

void init( Stack *s )
{
s->top = -1;
s->min = -1;

assist.top = -1;
}

void push( Stack *s ,int val )
{
if( full(s) )
{
printf("%s\n", "stack is full");
return;
}
if( (s->min == -1) || (val < s->min) )
{
s->min = val;
assist.data[++assist.top] = val;
}
s->data[++s->top] = val;
}

int pop( Stack *s )
{
int data;
if( empty(s) )
{
printf( "%s\n", "stack is empty" );
return -1;
}
data = s->data[s->top--];
if( data == assist.data[assist.top] )
{
s->min = assist.data[--assist.top];
}
return data;
}

bool full( Stack *s )
{
if( s->top == STACK_SIZE-1 )
{
return true;
}
return false;
}

bool empty( Stack *s )
{
if( s->top == -1 )
{
return true;
}
return false;
}

int min( Stack *s )
{
return s->min;
}

int main( int argc, char ** argv )
{
Stack s;
init( &s );
push( &s, 3);
std::cout << min( &s ) << std::endl;
push( &s, 4);
std::cout << min( &s ) << std::endl;
push( &s, 2);
std::cout << min( &s ) << std::endl;
push( &s, 1);
std::cout << min( &s ) << std::endl;
pop( &s );
std::cout << min( &s ) << std::endl;
pop( &s );
std::cout << min( &s ) << std::endl;
push( &s, 0);
std::cout << min( &s ) << std::endl;
return 0;
}

【结论】

作者