寻找数组中的最大值和最小值（编程之美2.10，包括最大值和次大值）

// 2_9.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <cassert>

#define INT_MIN -100000

//最大值和最小值
void min_max(int * arr, size_t len, int & min, int &max)
{
assert(arr);
assert(len>0);
int start = 0;
if(len%2 ==0)
{
if(arr[0]>arr[1])
{
min=arr[1];
max=arr[0];
}
else
{
min=arr[0];
max=arr[1];
}
start=2;
}
else
{
min=arr[0];
max=arr[1];
start = 1;
}
for(;start<len;start+=2)
{
if(arr[start]>arr[start+1])
{
if(arr[start]>max)
max = arr[start];
if(arr[start+1]<min)
min = arr[start+1];
}
else
{
if(arr[start+1]>max)
max = arr[start+1];
if(arr[start]<min)
min = arr[start];
}
}

}

//最大值和次大值，递归实现
void max_secondMax(int * arr, int left, int right, int & max, int &max2)
{
if(right == left)
{
max = arr[left];
max2 = INT_MIN;
return;
}
else if(right - left == 1)
{
if(arr[right] > arr[left])
{
max = arr[right];
max2 = arr[left];
return;
}
else
{
max = arr[left];
max2 = arr[right];
return;
}
}
int lmax, lmax2;
int rmax, rmax2;
max_secondMax(arr, left, left+(right-left)/2,lmax,lmax2);
max_secondMax(arr, left+(right-left)/2+1, right,rmax,rmax2);

if(lmax>rmax)
{
max = lmax;
if(lmax2 > rmax)
max2 = lmax2;
else
max2 = rmax;
}
else
{
max = rmax;
if(rmax2 > lmax)
max2 = rmax2;
else
max2 = lmax;
}

}

int _tmain(int argc, _TCHAR* argv[])
{
int arr[5] = {2,3,102,4,100};
int min,max;
min_max(arr,5,min,max);

printf("max:%d,min:%d\n",max,min);

int max2;
max_secondMax(arr,0,4,max,max2);

printf("max:%d,second max:%d\n",max,max2);

return 0;
}