SZU:B47 Big Integer II

Judge Info

• Memory Limit: 32768KB
• Case Time Limit: 10000MS
• Time Limit: 10000MS
• Judger: Normal

Description

Please calculate the answer of A*B, both A and B are integer.

Input

The first line of input contains , the number of test cases. There is only line for each test case. It contains two integers .

Output

For each test case, output A*B in one line.

Sample Input

3

1 2

1 1

-1 -1

Sample Output

2

1

1

 

Ps : 算法课的小练习，通过字符串处理。注意0就OK了。

 

 1 #include <stdio.h>

 2 #include <string.h>

 3 

 4 char A[200];

 5 char B[200];

 6 int C[200+200+1];

 7 

 8 char *revstr(char *str, int len){

 9     char *start = str;

10     char *end = str + len - 1;

11     char ch;

12     if(str != 0){

13         while(start < end){

14             ch = *start;

15             *start ++ = *end;

16             *end-- = ch;

17         }

18     }

19     return str;

20 }

21 

22 int main(int argc, char const *argv[])

23 {

24     int t, i, j, lenA, lenB, len, Amark, Bmark, mark;

25     scanf("%d", &t);

26     while(t--){

27 

28         mark=0;

29         Amark = 0;

30         Bmark = 0;

31 

32         memset(A, '0', sizeof(A));

33         memset(B, '0', sizeof(B));

34         memset(C, 0, sizeof(C));

35         scanf("%s", A);

36         scanf("%s", B);

37         lenA = strlen(A);

38         lenB = strlen(B);

39 

40         if(A[0] == '-'){

41             for(i=1;i<lenA;++i)

42                 A[i-1] = A[i];

43             A[i-1]= '\0';

44             A[i] = '0';

45             Amark = 1;

46             lenA--;

47         }

48 

49         if(B[0] == '-'){

50             for(i=1;i<lenB;++i)

51                 B[i-1] = B[i];

52             B[i-1] = '\0';

53             B[i] = '0';

54             Bmark = 1;

55             lenB--;

56         }

57         revstr(A,lenA);

58         revstr(B,lenB);

59         A[lenA] = '\0';

60         B[lenB] = '\0';

61         

62         for(i=0;i<lenB;++i){

63             for(j=0;j<lenA;++j){

64                 C[j+i]+=(B[i]-'0')*(A[j]-'0');

65             }    

66         }

67         len = lenA + lenB;

68         for(i=0;i<len;++i){

69             if(C[i] > 9){

70                 C[i+1]+=C[i]/10;

71                 C[i] %= 10;

72             }

73         }

74          while(!C[len-1]){

75                  len--;

76          }

77          //printf("len = %d\n", len);

78          if(len == 0){ printf("0\n"); continue;}

79          if(len > -1 && Amark != Bmark)

80              putchar('-');

81         for(i=len-1;i>=0;i--)

82             printf("%d", C[i]);

83         

84         printf("\n");

85     }

86 

87     return 0;

88 }