第一章 绪论
1.16
void print_descending(int x,int y,int z)//按从大到小顺序输出三个数
{
scanf("%d,%d,%d",&x,&y,&z);
if(x<y) x<->y; //<->为表示交换的双目运算符,以下同
if(y<z) y<->z;
if(x<y) x<->y; //冒泡排序
printf("%d %d %d",x,y,z);
}//print_descending
1.17
Status fib(int k,int m,int &f)//求k阶斐波那契序列的第m项的值f
{
int tempd;
if(k<2||m<0) return ERROR;
if(m<k-1) f=0;
else if (m==k-1 || m==k) f=1;
else
{
for(i=0;i<=k-2;i++) temp[i]=0;
temp[k-1]=1;temp[k]=1; //初始化
sum=1;
j=0;
for(i=k+1;i<=m;i++,j++) //求出序列第k至第m个元素的值
temp[i]=2*sum-temp[j];
f=temp[m];
}
return OK;
}//fib
分析: k阶斐波那契序列的第m项的值f[m]=f[m-1]+f[m-2]+......+f[m-k]
=f[m-1]+f[m-2]+......+f[m-k]+f[m-k-1]-f[m-k-1]
=2*f[m-1]-f[m-k-1]
所以上述算法的时间复杂度仅为O(m). 如果采用递归设计,将达到O(k^m). 即使采用暂存中间结果的方法,也将达到O(m^2).
1.18
typedef struct{
char *sport;
enum{male,female} gender;
char schoolname; //校名为'A','B','C','D'或'E'
char *result;
int score;
} resulttype;
typedef struct{
int malescore;
int femalescore;
int totalscore;
} scoretype;
void summary(resulttype result[ ])//求各校的男女总分和团体总分,假设结果已经储存在result[ ]数组中
{
scoretype score[MAXSIZE];
i=0;
while(result[i].sport!=NULL)
{
switch(result[i].schoolname)
{
case 'A':
score[ 0 ].totalscore+=result[i].score;
if(result[i].gender==0) score[ 0 ].malescore+=result[i].score;
else score[ 0 ].femalescore+=result[i].score;
break;
case 'B':
score[ 0 ].totalscore+=result[i].score;
if(result[i].gender==0) score[ 0 ].malescore+=result[i].score;
else score[ 0 ].femalescore+=result[i].score;
break;
…… …… ……
}
i++；
}
for(i=0;i<5;i++)
{
printf("School %d:\n",i);
printf("Total score of male:%d\n",score[i].malescore);
printf("Total score of female:%d\n",score[i].femalescore);
printf("Total score of all:%d\n\n",score[i].totalscore);
}
}//summary
1.19
Status algo119(int a[ARRSIZE])//求i!*2^i序列的值且不超过maxint
{
last=1;
for(i=1;i<=ARRSIZE;i++)
{
a[i-1]=last*2*i;
if((a[i-1]/last)!=(2*i)) reurn OVERFLOW;
last=a[i-1];
return OK;
}
}//algo119
分析:当某一项的结果超过了maxint时,它除以前面一项的商会发生异常.
1.20
void polyvalue()
{
float temp;
float *p=a;
printf("Input number of terms:");
scanf("%d",&n);
printf("Input value of x:");
scanf("%f",&x);
printf("Input the %d coefficients from a0 to a%d:\n",n+1,n);
p=a;xp=1;sum=0; //xp用于存放x的i次方
for(i=0;i<=n;i++)
{
scanf("%f",&temp);
sum+=xp*(temp);
xp*=x;
}
printf("Value is:%f",sum);
}//polyvalue