7道c练习题

花了我将近两个小时的时间。。。。。。。。。

/*
author:zhanglu
date:09/04/26
*/
#include <stdio.h>

/*
判断用户输入的数是否为质数？
*/
bool isPrimeNumber(int number)
{
	bool flag = true;
	for(int i = 2;i < number;++i)
	{
		if(number % i == 0)
		{
			flag = false;
			break;
		}
	}
	return flag;
}
void testPrimeNumber()
{
	int number,nClear;
	printf("请输入一个数字:\n");
	scanf("%d", &number);
	while(number < 0)
	{
		printf("请重新输入一个数字:\n");
		while((nClear = getchar()) != '\n' && nClear != EOF);
		scanf("%d", &number);
	}
	if(isPrimeNumber(number))
	{
		printf("%d是质数!\n", number);
	}else
	{
		printf("%d不是质数!\n", number);
	}
	
}
/*
求1000以内的素数之和
*/
void primeSum()
{
	int nSumPrime = 0,i = 2;
	do
	{
		if(isPrimeNumber(i))
		{
			nSumPrime += i;
		}
		++i;
	}while(i <= 1000);
	printf("1000以内素数之和为：%d\n", nSumPrime);
}
/*
列出用户输入的某个数的全部因子
*/
void splitNumber()
{
	int a,nClear;
	printf("请输入一个数字:\n");
	scanf("%d", &a);
	while(a < 0)
	{
		printf("请重新输入数字：\n");
		while((nClear = getchar()) != '\n' && nClear != EOF);
		scanf("%d", &a);
	}
	int i = 2;
	while(a > 1)
	{
		while(a % i == 0)
		{
			a /= i;
			printf("%d\n", i);
		}
		++i;
	}
}
/*
列出用户输入的某个数的分解和，分解为几个连续数的和
*/
void listSplitNumer()
{
	int number,nClear,nSum = 0;
	printf("请输入一个数字：\n");
	scanf("%d", &number);
	while(number < 0)
	{
		printf("请重新输入一个数字：\n");
		while((nClear = getchar()) != '\n' && nClear != EOF);
		scanf("%d", &number);
	}
	if(number % 2 == 0)
	{
		int halfNumber = number/2;
		printf("===================================\n");
		for(int i = halfNumber;i > 0;--i)
		{
			nSum = i;
			for(int j = i - 1;j > 0;--j)
			{
				nSum += j;
				if(nSum == number)
				{
					printf("%d = ", number);
					for(int k = j;k <= i;++k)
					{
						if(k == i)
						{
							printf("%d\n", k);
						}else
						{
							printf("%d+ ", k);
						}
					}
					nSum = 0;
					break;
				}else
				{
					if(nSum > number)
					{
						nSum = 0;
						break;
					}else
					{
						if(j == 1)
						{
							nSum = 0;
						}
					}
				}
			}
		}
	}else
	{
		printf("===================================\n");
		int halfNumber = number/2;
		printf("%d = %d + %d\n", number, halfNumber, halfNumber+1);
		for(int i = halfNumber;i > 0;--i)
		{
			nSum = i;
			for(int j = i - 1;j > 0;--j)
			{
				nSum += j;
				if(nSum == number)
				{
					printf("%d = ", number);
					for(int k = j;k <= i;++k)
					{
						if(k == i)
						{
							printf("%d\n", k);
						}else
						{
							printf("%d+ ", k);
						}
					}
					nSum = 0;
					break;
				}else
				{
					if(nSum > number)
					{
						nSum = 0;
						break;
					}else
					{
						if(j == 1)
						{
							nSum = 0;
						}
					}
				}
			}
		}
	}
}
/*
列出10000内的完全数
*/
void perfectNumber()
{
	int number = 10000;
	printf("%d = ", number);
	while(number != 1)
	{
		while(number % 2 == 0)
		{
			number /=2;
			if(number != 1)
			{
				printf("%d+ ", number);
			}else
			{
				printf("%d\n", number);
			}
			
			while(number != 1 && number % 2 != 0)
			{
				number /=2;
				number += 1;
				printf("%d+ ", number);
			}
		}
	}
}
/*
列出1000以内素数中的各位数字和为2的素数
*/
void screeningPrime()
{
	int primeDigit = 0;
	for(int i = 2;i <= 1000;++i)
	{
		if(isPrimeNumber(i))
		{
			primeDigit = i;
			int baiw = primeDigit / 100;
			int shiw = primeDigit / 10;
			int gew = primeDigit % 10;
			int num;
			if(baiw != 0)
			{
				shiw = (primeDigit % 100)/10;
				gew = (primeDigit % 100) % 10;
				num = baiw + shiw + gew;
				while(num != 2)
				{
					baiw = num / 100;
					shiw = num / 10;
					gew = num % 10;
					if(baiw != 0)
					{
						shiw = (primeDigit % 100)/10;
						gew = (primeDigit % 100) % 10;
						num = baiw + shiw + gew;
						if(num == 2)
						{
							printf("%d\n", primeDigit);
						}else
						{
							if(num / 10 == 0)
							{
								break;
							}
						}
						
					}else if(shiw != 0)
					{
						gew = num % 10;
						num = shiw + gew;
						if(num == 2)
						{
							printf("%d\n", primeDigit);
						}else
						{
							if(num / 10 == 0)
							{
								break;
							}
						}

					}else
					{
						num = gew;
						if(num == 2)
						{
							printf("%d\n", primeDigit);
						}else
						{
							break;
						}
					}
				}

			}else if(shiw != 0)
			{
				gew = num % 10;
				num = shiw + gew;
				if(num == 2)
				{
					printf("%d\n", primeDigit);
				}
			}else
			{
				num = gew;
				if(num == 2)
				{
					printf("%d\n", primeDigit);
				}
			}
		}
	}
}
/*
7只老鼠围成一个圈,从第一只开始吃，隔一只吃一只，求最后被吃的老鼠是第几只老鼠？
1  2   3   4    5
*/
void eatMice(int nMiceCout)
{
	int nMice[100] = {0};
	for(int j = 0;j < nMiceCout;j++)
	{
		nMice[j] = j+1;
	}
	int flag = 1;
	int i = 0, eatCount = 0, nMiceNumber;
	while(eatCount != nMiceCout)
	{
		if(i <= nMiceCout - 1)
		{
			if(flag == 1)
			{
				if(nMice[i] != 0)
				{
					nMice[i] = 0;
					++eatCount;
					if(eatCount == nMiceCout)
					{
						nMiceNumber = i+1;
					}
					++i;
					printf("flag = %d    i = %d\n", flag, i);
					flag = 0;
				}else
				{
					++i;
				}
			}else
			{
				if(nMice[i] != 0)
				{
					++flag;
				}
				++i;
			}
		}else
		{
			i = 0;
		}
	}
	printf("最后被吃的老鼠是第%d只老鼠\n", nMiceNumber);
}

int main(void)
{
	//testPrimeNumber();
	//primeSum();
	//perfectNumber();
	//screeningPrime();
	eatMice(10);

	return 0;
}

评论

3 楼 chirking 2009-06-29  

<pre name="code" class="c"># /*
# 7只老鼠围成一个圈,从第一只开始吃，隔一只吃一只，求最后被吃的老鼠是第几只老鼠？
# 1  2   3   4    5
# 约瑟夫环问题
# */ 

int main()
{
    int i, r=0, n=7, m=2;
    for(i=2; i&lt;=n; i++)
        r = (r+m)%i;
    printf("%d", r+1);
}</pre>
 

2 楼 sotlcs 2009-05-19  

一个小小的建议：
1.你说是C代码，那么C中是没有bool类型的。
2.判断一个数是不是素数，可以这样写，效率会高一些：（有写的不对的，多多包涵。）

#include <stdio.h>
#include <math.h>
int IsPrime(int x)
{ 	
	if (x == 1)return 0;
	else if (x == 2)return 1;
	else if (x % 2 == 0) return 0;
	else 
	{ 
		int i,bound = sqrt((double)x) + 1;
		for( i = 3; i < bound; i += 2)
		{
			if (x % i == 0)
				return 0;
		}
		return 1;
	}
}

int main()
{
	int n;
	printf("Please input a positive integer:");
	while (scanf( "%d",&n) && n) {
		if (n < 0) printf("Please input a positive integer:");
		else 
		{
			if(IsPrime(n))
				printf("Yes\n");
			else 
				printf("No\n");	
			printf("Please input a positive integer:");
		}
	}
	return 0;
}

3.如果你想计算[0,n]中所有素数的和，那可以一边寻找，一遍构造素数数组，这个数组对后面整数的素数判断有好处，这样检查起来速度会更快。当然你可以先构造好数组，再计算，但是个人觉得，两者差不多。

#include <stdio.h>
#include <math.h>
int Ps[100];
int index = 2;
int IsPrime(int x)
{ 	
	if (x == 1)return 0;
	else if (x == 2)return 1;
	else if (x % 2 == 0) return 0;
	else 
	{ 
		int i,bound = sqrt((double)x) + 1;
		for( i = 1; Ps[i] < bound; i ++)
		{
			if (x % Ps[i] == 0)
				return 0;
		}
		Ps[index++] = x;
		return 1;
	}
}

int SumPrime(int n)
{
	int i, sum = 0;
	for(i = 2; i <= n; i++)
		if(IsPrime(i))
			sum += i;
	return sum;
}

int main()
{
	int n;
    Ps[0] = 2;Ps[1] = 3;
	printf("Please input a positive integer:");
	while (scanf( "%d",&n) && n) {
		if (n < 0) printf("Please input a positive integer:");
		else 
		{
			printf("The Sum of primers between 0 and %d is: %d\n",n,SumPrime(n));			
			printf("Please input a positive integer:");
		}
	}
	return 0;
}

1 楼 erlengleng 2009-05-18  

学习了，我2个小时也弄不出来，我得2天，顺便问问C开发，一般用什么IDE?