FAFU-OJ 1004 大数乘积

直接上源代码：

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#include <string.h>
#include <stdio.h>
#define N 200
char s[N] = {0},c[N] = {0};
int sn[N],sc[N],cn[N];
int monitor = 0;
int last = 0;

void cheng(int y,int j)					//进行乘法运算


{
	int i = j;
	while(sn[i-j] != -1)
	{
		cn[i] = sn[i-j] * y + cn[i];
		i++;	
	}
	i = 0;
	while(i < N)
	{			
		if(cn[i] >= 10)
		{
			cn[i+1] = cn[i+1] + cn[i] / 10;
			cn[i] = cn[i] % 10;
		}
		i++;
	}
///		printf("cheng{} done!n");

}

void locat(void)                           //判断小数位有几位


{
	int i;
	int monitors,monitorc;
	int flags = 0,flagc = 0;
	int lens = strlen(s);
	int lenc = strlen(c);
	i = 0;
	while(i < lens)
	{
		if(s[i] == '.')
		{
			flags = 1;
			monitors = lens - i - 1;
			break;
		}
		i++;
	}
	i = 0;
	while(i < lenc)
	{
		if(c[i] == '.')
		{
			flagc = 1;
			monitorc = lenc - i - 1;
			break;
		}
		i++;
	}
	
	if(flags)
		monitor += monitors;
	if(flagc)
		monitor += monitorc;

//		printf("locat{} done!n");

}

bool doc(void)                          //判断是否整个数非0

{
	int i = N - 1;
	while(i >= 0)
	{
		i--;
		if(cn[i] > 0)
			return true;
	}
	return false;
}

void dec(void)							//判断是否需要小数位前补0


{
	int i = N - 1,lencn;
	while(cn[i] == 0 && i >= 0)
	{
		i--;
	}
	lencn = i + 1;
//	printf("%dn",lencn);



	if(lencn-1 < monitor )
	{
		printf("0.");
		lencn++;
	}
	while(lencn <= monitor)
	{
		printf("0");
		lencn++;
	}

//		printf("dec{} done!n");

}

void lastzero()												//判断小数点后末几位是否有0，有则删除

{
	int i = 0;
	if(monitor > 0)
	{
		while(cn[i] == 0 && i + 1 <= monitor)
		{
			i++;
			last++;
		}
	}

//		printf("lastzero{} done!n");

}



int main()
{
	int i,j;
	int flag;

//	freopen("data11.in","r",stdin);

//	freopen("data11(2).out","w",stdout);

	
	while(scanf("%s%s",&s,&c) == 2)									
	{
		flag = 0;
		for(i = 0; i < N; i++)
		{
			sn[i] = -1;
			sc[i] = -1;
			cn[i] = 0;
		}
		int i;
		int beicheng = 1;
		int lens = strlen(s);
		int lenc = strlen(c);

		i = lens - 1;
		j = 0;
		while(i >= 0)
		{
			if(s[i] == '.')
			{
				i--;
				continue;
			}
			sn[j] = (int)s[i] - 48;
			i--;
			j++;
		}

		i = lenc - 1;
		j = 0;
		while(i >= 0)
		{
			if(c[i] == '.')
			{
				i--;
				continue;
			}
			sc[j] = (int)c[i] - 48;
			i--;
			j++;
		}

		i  = 0;
		while(sc[i] >= 0)
		{
			beicheng = sc[i];
			cheng(beicheng,i);
			i++;
		}
		
//		printf("%dn",beicheng);



		if(!doc())
		{
			printf("0n");
		}
		else
		{
			locat();
			lastzero();
			dec();
		
			for(i = N - 1; i >= last; i--)
			{
				if(cn[i] > 0)
				{
					while(i >= last)
					{
						printf("%d",cn[i]);				
					
						if(monitor > 0 && i == monitor && i - last > 0)
							printf(".");
						
						i--;
					}
				}
			}
			printf("n");
		}


	
/*
		for(i = N - 1; i >= 0; i--)
		{
			printf("%d",cn[i]);
		}
		printf("n");
/*
		for(i = N - 1; i >= 0; i--)
		{
			if(sc[i] != -1)
			{
				printf("%d",sc[i]);
			}
		}
		printf("n");
*/


		memset(s,N);
		memset(c,N);
		monitor = 0;
		last = 0;
	}

	return 0;
}