1、读文件 file1.txt 的内容(例如)：

12

34

56

输出到 file2.txt：

56

34

12

#include

#include

int main(void)

{

int MAX = 10;

int *a = (int *)malloc(MAX * sizeof(int));

int *b;

FILE *fp1;

FILE *fp2;

fp1 = fopen("a.txt","r");

if(fp1 == NULL)

{printf("error1");

exit(-1);

}

fp2 = fopen("b.txt","w");

if(fp2 == NULL)

{printf("error2");

exit(-1);

}

int i = 0;

int j = 0;

while(fscanf(fp1,"%d",&a[i]) != EOF)

{

i++;

j++;

if(i >= MAX)

{

MAX = 2 * MAX;

b = (int*)realloc(a,MAX * sizeof(int));

if(b == NULL)

{

printf("error3");

exit(-1);

}

a = b;

}

}

for(;--j >= 0;)

fprintf(fp2,"%d\n",a[j]);

fclose(fp1);

fclose(fp2);

return 0;

}

2、写一段程序，找出数组中第 k 大小的数，输出数所在的位置，

函数接口为：int find_orderk(const int* narry,const int n,const int k)

要求算法复杂度不能是 O(n^2)

可以先用快速排序进行排序，其中用另外一个进行地址查找代码如下，在 VC++6.0 运行通过。

//快速排序

#include

usingnamespacestd;

intPartition (int*L,intlow,int high)

{

inttemp = L[low];

intpt = L[low];

while (low < high)

{

while (low < high && L[high] >= pt)

--high;

L[low] = L[high];

while (low < high && L[low] <= pt)

++low;

L[low] = temp;

}

L[low] = temp;

returnlow;

}

voidQSort (int*L,intlow,int high)

{

if (low < high)

{

intpl = Partition (L,low,high);

QSort (L,low,pl - 1);

QSort (L,pl + 1,high);

}

}

intmain ()

{

intnarry[100],addr[100];

intsum = 1,t;

cout << "Input number:" << endl;

cin >> t;

while (t != -1)

{

narry[sum] = t;

addr[sum - 1] = t;

sum++;

cin >> t;

}

sum -= 1;

QSort (narry,1,sum);

for (int i = 1; i <= sum;i++)

cout << narry[i] << '\t';

cout << endl;

intk;

cout << "Please input place you want:" << endl;

cin >> k;

intaa = 1;

intkk = 0;

for (;;)

{

if (aa == k)

break;

if (narry[kk] != narry[kk + 1])

{

aa += 1;

kk++;

}

}

cout << "The NO." << k << "number is:" << narry[sum - kk] << endl;

cout << "And it's place is:" ;

for (i = 0;i < sum;i++)

{

if (addr[i] == narry[sum - kk])

cout << i << '\t';

}

return0;

}