网教 8.a+b

题目描述

给出两个非负实数a和b,求a+b

输入

一组用例,包括两个长度不大于400的非负实数a和b

输出

输出一行为a+b的最简形式,即没有前置0后置0,小数部分为0则省略小数点

样例输入

1

1

样例输出

2

评论:对于强神的题,一向都是敢写敢WA,敢写敢T,敢写敢RE……

题解:

开题的一瞬间,我感觉这题我做过,然后就兴高采烈地交(哇)了三发……

以前做的是整数想加,强神这次改成了实数相加……

不过总之我的整数相加的一部分还能用……

然后我就只写了小数相加的一部分,不是特别难。但是要注意的一点是进位的问题,如果小数进位了,两个小数相加变成了1.xxxx,那就得再加一次。我一开始想的是先让a1和b1相加,如果刚刚说的成立的话就用res1与数组"1"相加,即让res1加1.

但是在我写的里面出了个bug,因为我是想让长的和短的换位置(以简化步骤,让a总是短的,b总是长的),但是这样一来传入时b数组的长度不够,就会RE。一开始我还不知道为什么RE,后来自己编了个用例才知道原来这也会错。

发现之后我就知道了不能偷懒,还是得老老实实地写一个res1和1的加法。所以最后我把这个加法写到了if语句里面,而add1就只在整数相加的时候运行了。然后再加上自己的整数相加代码,这个就完了。

其实我也尝试着写过add1函数,但是WA了,感觉是因为有一些特殊情况没考虑之类的。

也在前缀和后缀省去0上错过一次。

错误代码1:

#include<stdio.h> //这个代码是我自己写add1函数的时候错的代码
#include<string.h> 
char a[1000], b[1000]; 
char a1[1000], a2[1000], b1[1000], b2[1000]; 
char res1[1000], res2[1000]; 
int flag = 0; 
 
void add1() 
{ 
 char res[1000]; 
    memset(res, 0, sizeof(res)); 
   int index, num1, num2, num; 
    num1 = strlen(a1); 
 num2 = strlen(b1); 
 if (num1 > num2) 
    { 
      char tmp[1000]; 
        int i; 
     for (i = 0; i < num1; i++) 
          tmp[i] = a1[i]; 
        tmp[i] = '\0'; 
     for (i = 0; i < num2; i++) 
          a1[i] = b1[i]; 
     a1[i] = '\0'; 
      for (i = 0; i < num1; i++) 
          b1[i] = tmp[i]; 
        b1[i] = '\0'; 
      int t; 
     t = num1; 
      num1 = num2; 
       num2 = t; 
  }//num1<=num2 
   int i; 
 for (i = 0; i < num1; i++)//记录偏移量 
   { 
      res[num2  - i] += a1[num1 - 1 - i] - '0' + b1[num2 - 1 - i]; 
       if (res[num2  - i]>'9') 
     { 
          res[num2  - i] -= 10; 
          res[num2  - i-1]++; 
        } 
  } 
  for (i = num1; i <num2; i++)//i记录偏移量 
    { 
      res[num2 - i] = res[num2 - i] + b1[num2 - i - 1]; 
      if (res[num2-i] > '9') 
      { 
          res[num2-i] = res[num2-i] - 10; 
            res[num2-i - 1]++; 
     } 
  } 
  if (res[0] == '\0') 
    { 
      for (i = 0; i < num2; i++) 
      res[i] = res[i + 1]; 
       res[i] = '\0'; 
 } 
  if (res[0] == 1) 
       res[0] = '1'; 
  strcpy(res1, res); 
} 
 
void add2() 
{ 
    int num1, num2; 
    num1 = strlen(a2); 
 num2 = strlen(b2); 
 char tmp[1000]; 
    if (num1 > num2)//a比b长,就把a和b换位置 
 { 
      int i; 
     for (i = 0; i < num1; i++) 
          tmp[i] = a2[i]; 
        tmp[i] = '\0'; 
     for (i = 0; i < num2; i++) 
          a2[i] = b2[i]; 
     a2[i] = '\0'; 
      for (i = 0; i < num1; i++) 
          b2[i] = tmp[i]; 
        b2[i] = '\0'; 
      int t; 
     t = num1; 
      num1 = num2; 
       num2 = t; 
  }//现在a比b短,num1是a,num2是b 
    int i; 
 for (i = num1; i < num2; i++) 
       res2[i] = b2[i]; 
   for (i = num1-1; i >= 0; i--) 
   { 
      res2[i] = res2[i] + b2[i] - '0' + a2[i]; 
       if (res2[i]>'9') 
        { 
          res2[i] = res2[i] - 10; 
            if (i != 0) 
                res2[i - 1]++; 
         else 
               flag = 1; 
      } 
  } 
  int num = strlen(res2); 
    while (num!=0&&res2[num - 1] == '0') 
   { 
      res2[num - 1] = '\0'; 
      num--; 
 } 
} 
 
int main() 
{ 
  scanf("%s", &a); 
   scanf("%s", &b); 
   int lena, lenb; 
    lena = strlen(a); 
  lenb = strlen(b); 
  memset(res1, 0, sizeof(res1)); 
 memset(res2, 0, sizeof(res2)); 
 int i, x = -1, y = -1;//-1代表它们是整数,没有小数点 
    for (i = 0; i < lena;i++) 
   if (a[i] == '.') 
   { 
      x = i; 
     break; 
 } 
  if (x != -1) 
   { 
      for (i = 0; i < x; i++) 
         a1[i] = a[i]; 
      for (i = x + 1; i < lena; i++) 
          a2[i - x - 1] = a[i]; 
  } 
  else 
   { 
      strcpy(a1, a); 
     a2[0] = '\0'; 
      a2[1] = '\0'; 
  } 
 
 for (i = 0; i < lenb; i++) 
  if (b[i] == '.') 
   { 
      y = i; 
     break; 
 } 
  if (y != -1) 
   { 
      for (i = 0; i < y; i++) 
         b1[i] = b[i]; 
      for (i = y + 1; i < lenb; i++) 
          b2[i - y - 1] = b[i]; 
  } 
  else 
   { 
      strcpy(b1, b); 
     b2[0] = '\0'; 
      b2[1] = '\0'; 
  }//现在a1,b1装的是整数部分,a2,b2装的是小数部分。 
    add2(); 
    add1(); 
    if (flag) 
  { 
      int num = strlen(res1);//num>=1 
     res1[num - 1]++; 
       for (i = num - 1; i > 0;i--) 
        if (res1[i] > '9') 
      { 
          res1[i] -= 10; 
         res1[i-1]++; 
       } 
      if (res1[0] > '9') 
      { 
          res1[0] -= 10; 
         for (i = num - 1; i >= 0; i--) 
              res1[i + 1] = res1[i]; 
         res1[0] = '1'; 
     } 
  } 
  if (strcmp(res2, "0") == 0||strcmp(res2,"\0")==0) 
      printf("%s\n", res1); 
  else 
       printf("%s.%s\n", res1, res2); 
}  

错误代码2:

#include<stdio.h> //总是RE
#include<string.h> 
char a[1000], b[1000]; 
char a1[1000], a2[1000], b1[1000], b2[1000]; 
char res1[1000], res2[1000]; 
int flag = 0; 
 
void add1(char a1[],char b1[]) 
{ 
  char res[1000]; 
    memset(res, 0, sizeof(res)); 
   int index, num1, num2, num; 
    num1 = strlen(a1); 
 num2 = strlen(b1); 
 if (num1 > num2) 
    { 
      char tmp[1000]; 
        strcpy(tmp, a1); 
       strcpy(a1, b1); 
        strcpy(b1, tmp); 
       int t; 
     t = num1; 
      num1 = num2; 
       num2 = t; 
  }//num1<=num2 
   int i; 
 for (i = 0; i < num1; i++)//记录偏移量 
   { 
      res[num2  - i] += a1[num1 - 1 - i] - '0' + b1[num2 - 1 - i]; 
       if (res[num2  - i]>'9') 
     { 
          res[num2  - i] -= 10; 
          res[num2  - i-1]++; 
        } 
  } 
  for (i = num1; i <num2; i++)//i记录偏移量 
    { 
      res[num2 - i] = res[num2 - i] + b1[num2 - i - 1]; 
      if (res[num2-i] > '9') 
      { 
          res[num2-i] = res[num2-i] - 10; 
            res[num2-i - 1]++; 
     } 
  } 
  if (res[0] == '\0') 
    { 
      for (i = 0; i < num2; i++) 
      res[i] = res[i + 1]; 
       res[i] = '\0'; 
 } 
  if (res[0] == 1) 
       res[0] = '1'; 
  strcpy(res1, res); 
} 
 
void add2() 
{ 
    int num1, num2; 
    num1 = strlen(a2); 
 num2 = strlen(b2); 
 char tmp[1000]; 
    if (num1 > num2)//a比b长,就把a和b换位置 
 { 
      strcpy(tmp, a2); 
       strcpy(a2, b2); 
        strcpy(b2, tmp); 
       int t; 
     t = num1; 
      num1 = num2; 
       num2 = t; 
  }//现在a比b短,num1是a,num2是b 
    int i; 
 for (i = num1; i < num2; i++) 
       res2[i] = b2[i]; 
   for (i = num1-1; i >= 0; i--) 
   { 
      res2[i] = res2[i] + b2[i] - '0' + a2[i]; 
       if (res2[i]>'9') 
        { 
          res2[i] = res2[i] - 10; 
            if (i != 0) 
                res2[i - 1]++; 
         else 
               flag = 1; 
      } 
  } 
  int num = strlen(res2); 
    while (num!=0&&res2[num - 1] == '0') 
   { 
      res2[num - 1] = '\0'; 
      num--; 
 } 
} 
 
int main() 
{ 
  scanf("%s", &a); 
   scanf("%s", &b); 
   int lena, lenb; 
    lena = strlen(a); 
  lenb = strlen(b); 
  memset(res1, 0, sizeof(res1)); 
 memset(res2, 0, sizeof(res2)); 
 int i, x = -1, y = -1;//-1代表它们是整数,没有小数点 
    for (i = 0; i < lena;i++) 
   if (a[i] == '.') 
   { 
      x = i; 
     break; 
 } 
  if (x != -1) 
   { 
      for (i = 0; i < x; i++) 
         a1[i] = a[i]; 
      for (i = x + 1; i < lena; i++) 
          a2[i - x - 1] = a[i]; 
  } 
  else 
   { 
      strcpy(a1, a); 
     a2[0] = '\0'; 
      a2[1] = '\0'; 
  } 
 
 for (i = 0; i < lenb; i++) 
  if (b[i] == '.') 
   { 
      y = i; 
     break; 
 } 
  if (y != -1) 
   { 
      for (i = 0; i < y; i++) 
         b1[i] = b[i]; 
      for (i = y + 1; i < lenb; i++) 
          b2[i - y - 1] = b[i]; 
  } 
  else 
   { 
      strcpy(b1, b); 
     b2[0] = '\0'; 
      b2[1] = '\0'; 
  }//现在a1,b1装的是整数部分,a2,b2装的是小数部分。 
    add2(); 
    add1(a1, b1); 
  if (flag) 
      add1(res1, "1"); 
   if (strcmp(res2, "0") == 0||strcmp(res2,"\0")==0) 
      printf("%s\n", res1); 
  else 
       printf("%s.%s\n", res1, res2); 
}  

AC代码:

#include<stdio.h>
#include<string.h>
char a[1000], b[1000];
char a1[1000], a2[1000], b1[1000], b2[1000];
char res1[1000], res2[1000];
int flag = 0;

void add1()
{
	char res[1000];
	memset(res, 0, sizeof(res));
	int index, num1, num2, num;
	num1 = strlen(a1);
	num2 = strlen(b1);
	if (num1 > num2)
	{
		for (index = 0; index < num2; index++)
		{
			if (a1[num1 - 1 - index] - '0' + b1[num2 - 1 - index] - '0' > 9)
			{
				a1[num1 - 2 - index]++;
				a1[num1 - 1 - index] = a1[num1 - 1 - index] - 10;
			}
			res[num1 - 1 - index] = a1[num1 - 1 - index] - '0' + b1[num2 - 1 - index];
		}

		for (index = num1 - num2 - 1; index > 0; index--)
		{
			if (a1[index] - '0' > 9)
			{
				a1[index] = a1[index] - 10;
				a1[index - 1]++;
			}
			res[index] = a1[index];
		}
		if (a1[0] - '0' > 9)
		{
			res[0] = a1[0] - 10;
			for (num = num1; num > 0; num--)
				res[num] = res[num - 1];
			res[0] = '1';
		}
		else
		{
			res[0] = a1[0];
		}
		num = strlen(res);
		while (res[0] == '0')
		{
			for (index = 0; index < num - 1; index++)
				res[index] = res[index + 1];
			res[num - 1] = '\0';
		}
		if (strcmp(res, "\0") == 0)
			res[0] = '0';
	}
	else if (num1<num2)//把上面的复制下来,改一下数组名即可 
	{
		for (index = 0; index < num1; index++)
		{
			if (a1[num1 - 1 - index] - '0' + b1[num2 - 1 - index] - '0' > 9)
			{
				b1[num2 - 2 - index]++;
				b1[num2 - 1 - index] = b1[num2 - 1 - index] - 10;
			}
			res[num2 - 1 - index] = a1[num1 - 1 - index] - '0' + b1[num2 - 1 - index];
		}

		for (index = num2 - num1 - 1; index > 0; index--)
		{
			if (b1[index] - '0' > 9)
			{
				b1[index] = b1[index] - 10;
				b1[index - 1]++;
			}
			res[index] = b1[index];
		}
		if (b1[0] - '0' > 9)
		{
			res[0] = b1[0] - 10;
			for (num = num2; num > 0; num--)
				res[num] = res[num - 1];
			res[0] = '1';
		}
		else
		{
			res[0] = b1[0];
		}
		num = strlen(res);
		while (res[0] == '0')
		{
			for (index = 0; index < num - 1; index++)
				res[index] = res[index + 1];
			res[num - 1] = '\0';
		}
		if (strcmp(res, "\0") == 0)
			res[0] = '0';
	}
	else if (num1 == num2)
	{
		for (index = num1 - 1; index > 0; index--)
		{
			if (a1[index] - '0' + b1[index] - '0' > 9)
			{
				b1[index - 1]++;
				b1[index] = b1[index] - 10;
			}
			res[index] = a1[index] - '0' + b1[index];
		}
		if (a1[index] - '0' + b1[index] - '0' > 9)
		{
			for (num = num1; num > 0; num--)
				res[num] = res[num - 1];
			res[0] = '1';
			b1[index] = b1[index] - 10;
			index++;
		}
		res[index] = a1[0] - '0' + b1[0];
		num = strlen(res);
		while (res[0] == '0')
		{
			for (index = 0; index < num - 1; index++)
				res[index] = res[index + 1];
			res[num - 1] = '\0';
		}
		if (strcmp(res, "\0") == 0)
			res[0] = '0';
	}
	strcpy(res1, res);
}

void add2()
{
	int num1, num2;
	num1 = strlen(a2);
	num2 = strlen(b2);
	char tmp[1000];
	if (num1 > num2)//a比b长,就把a和b换位置
	{
		int i;
		for (i = 0; i < num1; i++)
			tmp[i] = a2[i];
		tmp[i] = '\0';
		for (i = 0; i < num2; i++)
			a2[i] = b2[i];
		a2[i] = '\0';
		for (i = 0; i < num1; i++)
			b2[i] = tmp[i];
		b2[i] = '\0';
		int t;
		t = num1;
		num1 = num2;
		num2 = t;
	}//现在a比b短,num1是a,num2是b
	int i;
	for (i = num1; i < num2; i++)
		res2[i] = b2[i];
	for (i = num1 - 1; i >= 0; i--)
	{
		res2[i] = res2[i] + b2[i] - '0' + a2[i];
		if (res2[i]>'9')
		{
			res2[i] = res2[i] - 10;
			if (i != 0)
				res2[i - 1]++;
			else
				flag = 1;
		}
	}
	int num = strlen(res2);
	while (num != 0 && res2[num - 1] == '0')
	{
		res2[num - 1] = '\0';
		num--;
	}
}

int main()
{
	scanf("%s", &a);
	scanf("%s", &b);
	int lena, lenb;
	lena = strlen(a);
	lenb = strlen(b);
	memset(res1, 0, sizeof(res1));
	memset(res2, 0, sizeof(res2));
	int i, x = -1, y = -1;//-1代表它们是整数,没有小数点
	for (i = 0; i < lena; i++)
	if (a[i] == '.')
	{
		x = i;
		break;
	}
	if (x != -1)
	{
		for (i = 0; i < x; i++)
			a1[i] = a[i];
		for (i = x + 1; i < lena; i++)
			a2[i - x - 1] = a[i];
	}
	else
	{
		strcpy(a1, a);
		a2[0] = '\0';
		a2[1] = '\0';
	}

	for (i = 0; i < lenb; i++)
	if (b[i] == '.')
	{
		y = i;
		break;
	}
	if (y != -1)
	{
		for (i = 0; i < y; i++)
			b1[i] = b[i];
		for (i = y + 1; i < lenb; i++)
			b2[i - y - 1] = b[i];
	}
	else
	{
		strcpy(b1, b);
		b2[0] = '\0';
		b2[1] = '\0';
	}//现在a1,b1装的是整数部分,a2,b2装的是小数部分。
	add2();
	add1();
	if (flag)
	{
		int num = strlen(res1);//num>=1
		res1[num - 1]++;
		for (i = num - 1; i > 0; i--)
		if (res1[i] > '9')
		{
			res1[i] -= 10;
			res1[i - 1]++;
		}
		if (res1[0] > '9')
		{
			res1[0] -= 10;
			for (i = num - 1; i >= 0; i--)
				res1[i + 1] = res1[i];
			res1[0] = '1';
		}
	}
	if (strcmp(res2, "0") == 0 || strcmp(res2, "\0") == 0)
		printf("%s\n", res1);
	else
		printf("%s.%s\n", res1, res2);
}

都是一两百行……心累啊……

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