谭浩强第六章习题答案

谭浩强的第六章是循环，拿来练练手，程序是亲手写的，不一定是最优的，但一定对。另外12、13、15感觉比较扯就没写。

下面是代码：

//1.cpp
#include <stdio.h>
#define MAX(m,n) (((m) > (n) ? (m) : (n)))
#define MIN(m,n) (((m) < (n) ? (m) : (n)))

int main(void)
{
	int m, n;
	int i;
	int a, b;
	printf("Input m and n:\n");
	scanf("%d %d",&m,&n);
	for(i=MIN(m,n);i>0;i--)
	{
		if(!(m%i) && !(n%i))
			break;
	}
	a=i;
	for(i=MAX(m,n);;i++)
	{
		if(!(i%m) && !(i%n))
			break;
	}
	b=i;
	printf("a=%d\tb=%d\n",a,b);
	return 0;
}

//2.cpp
#include <stdio.h>

int main(void)
{
	char c;
	int num=0, letter=0, blank=0, digit=0, other=0;

	while((c=getchar()) != '\n')
	{
		num++;
		if((c>='a' && c <='z') || (c>='A' && c<='Z'))
			letter++;
		else if(c>='0' && c <='9')
			digit++;
		else if(c==' ')
			blank++;
		else
			other++;
	}
	printf("There are %d characters,%d letters,%d digits, %d blanks,%d other characters.\n)"
		,num,letter,digit,blank,other);
	return 0;
}

//3.cpp
#include <stdio.h>

int main(void)
{
	int a, n, tmp, sum;
	a=n=sum=tmp=0;
	printf("input a and n:\n");
	scanf("%d %d", &a, &n);
	for(int i=0; i<n; i++)
	{
		tmp = tmp * 10 + a;
		sum += tmp;
	}
	printf("sum = %d\n", sum);
	return 0;
}

//4.cpp
#include <stdio.h>

int main(void)
{
	int n;
	long tmp=1, sum=0;
	printf("input n:\n");
	scanf("%d", &n);
	for(int i=1; i<=n; i++)
	{
		tmp = tmp * i;
		sum +=tmp;
	}
	printf("sum = %d\n", sum);
	return 0;
}

//5.cpp
#include <stdio.h>

int main(void)
{
	int k, sum1=0;
	float sum=0;
	k = 100;
	for(int i=1; i<=k; i++)
	{
		sum1 += i;
	}
	k = 50;
	for(i=1; i<=k; i++)
	{
		sum1 += i * i;
	}
	k = 10;
	for(i=1; i<=k; i++)
	{
		sum += 1.0 / i;
	}
	sum += sum1;
	printf("sum = %.2f\n", sum);
	return 0;
}

//6.cpp
#include <stdio.h>

int main()
{
	int num, tmp;
	for(num=100; num<1000; num++)
	{
		tmp = (num/100)*(num/100)*(num/100) + (num%100/10)*(num%100/10)*(num%100/10) + (num%10)*(num%10)*(num%10);
		if(num == tmp)
			printf("%d\t",num);
	}
	printf("\n");
	
	return 0;
}

//7.cpp
#include <stdio.h>

int main()
{
	int i, j, k=0;
	int num, sum=0;
	int p[5];	//先运行一次根据k的值设置数组p的元素个数
	printf("Input the max num:\n");
	scanf("%d",&num);
	for (i=1; i<=num; i++)
	{
		for (j=1; j<=i/2; j++)
		{
			if (!(i%j))
			{
				sum += j;
			}
			if(sum > i)
				break;
		}
		if (sum == i)
		{
			p[k++] = i;
		}
		sum = 0;
	}
	for (i=0; i<k; i++)
	{
		printf("%d its factors are",p[i]);
		for (j=1; j<=p[i]/2; j++)
		{
			if (!(p[i]%j))
			{
				printf(" %d,",j);
			}
		}
		printf("\n");
	}
	//printf("k=%d",k);
	//printf("\n");
	return 0;
}

//8.cpp
#include <STDIO.H>
#define NUM 20

int main()
{
	int a[NUM]={2,3};
	int b[NUM]={1,2};
	float sum=2.0+3.0/2;
	for (int i=2; i<NUM; i++)
	{
		a[i] = a[i-1] + a[i-2];
		b[i] = a[i-1];
		sum += (float)a[i] / b[i];
	}
	printf("sum=%.3f\n",sum);
	
	return 0;
}

//9.cpp
#include <STDIO.H>
#define HIGHT 100

int main()
{
	float h=HIGHT;
	float sum=0.0;

	for (int i=0; i<10; i++)
	{
		sum += h;
		h = h / 2;
	}
	printf("sum=%.2fm,h=%.2fm\n",sum,h);
	return 0;
}

//10.cpp
#include <STDIO.H>

int main()
{
	int num=1;
	for (int i=1; i<10; i++)
	{
		num = (num + 1) * 2;
	}
	printf("num=%d\n",num);
	
	return 0;
}

//11.cpp
#include <math.h>
#include <stdio.h>

int main()
{
	float x1,x2, a;
	printf("Input a:\n");
	scanf("%f",&a);
	x1 = a / 2;
	x2 = (x1 + a/x1) / 2;
	while (fabs(x1-x2) >= 1e-5)
	{
		x1 = x2;
		x2 = (x1 + a / x1) / 2;
	}
	printf("x=%.3f\n",x2);

	return 0;
}

//14.cpp
#include <STDIO.H>

int main()
{
	int a,i,j,k;
	for (i=0; i<4; i++)
	{
		for (j=0;j<3-i;j++)
			printf("  ");
		for(k=0;k<2*i+1;k++)
			printf("* ");
		printf("\n");
	}
	for(i=0; i<3; i++)
	{
		for (j=0; j<i+1; j++)
			printf("  ");
		for (k=0; k<5-2*i; k++)
			printf("* ");
		printf("\n");
	}
	return 0;
}