題目描述
給出兩個非負實數a和b，求a+b
輸入
一組用例，包括兩個長度不大於400的非負實數a和b
輸出
輸出一行爲a+b的最簡形式，即沒有前置0後置0，小數部分爲0則省略小數點
樣例輸入
1
1
樣例輸出
2
評論：對於強神的題，一向都是敢寫敢WA，敢寫敢T，敢寫敢RE……
題解：
開題的一瞬間，我感覺這題我做過，然後就興高采烈地交（哇）了三發……
以前做的是整數想加，強神這次改成了實數相加……
不過總之我的整數相加的一部分還能用……
然後我就只寫了小數相加的一部分，不是特別難。但是要注意的一點是進位的問題，如果小數進位了，兩個小數相加變成了1.xxxx，那就得再加一次。我一開始想的是先讓a1和b1相加，如果剛剛說的成立的話就用res1與數組"1"相加，即讓res1加1.
但是在我寫的裏面出了個bug，因爲我是想讓長的和短的換位置（以簡化步驟，讓a總是短的，b總是長的），但是這樣一來傳入時b數組的長度不夠，就會RE。一開始我還不知道爲什麼RE，後來自己編了個用例才知道原來這也會錯。
發現之後我就知道了不能偷懶，還是得老老實實地寫一個res1和1的加法。所以最後我把這個加法寫到了if語句裏面，而add1就只在整數相加的時候運行了。然後再加上自己的整數相加代碼，這個就完了。
其實我也嘗試着寫過add1函數，但是WA了，感覺是因爲有一些特殊情況沒考慮之類的。
也在前綴和後綴省去0上錯過一次。
錯誤代碼1：
#include<stdio.h> //這個代碼是我自己寫add1函數的時候錯的代碼
#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++)//記錄偏移量
{
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記錄偏移量
{
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長，就把a和b換位置
{
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;
}//現在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代表它們是整數，沒有小數點
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';
}//現在a1,b1裝的是整數部分，a2,b2裝的是小數部分。
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);
} 錯誤代碼2：
#include<stdio.h> //總是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++)//記錄偏移量
{
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記錄偏移量
{
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長，就把a和b換位置
{
strcpy(tmp, a2);
strcpy(a2, b2);
strcpy(b2, tmp);
int t;
t = num1;
num1 = num2;
num2 = t;
}//現在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代表它們是整數，沒有小數點
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';
}//現在a1,b1裝的是整數部分，a2,b2裝的是小數部分。
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代碼：
#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)//把上面的複製下來，改一下數組名即可
{
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長，就把a和b換位置
{
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;
}//現在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代表它們是整數，沒有小數點
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';
}//現在a1,b1裝的是整數部分，a2,b2裝的是小數部分。
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);
}都是一兩百行……心累啊……
