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。

#include <stdio.h>
#include <string.h>

char A[200];
char B[200];
int C[200+200+1];

char *revstr(char *str, int len){
    char *start = str;
    char *end = str + len - 1;
    char ch;
    if(str != 0){
        while(start < end){
            ch = *start;
            *start ++ = *end;
            *end-- = ch;
        }
    }
    return str;
}

int main(int argc, char const *argv[])
{
    int t, i, j, lenA, lenB, len, Amark, Bmark, mark;
    scanf("%d", &t);
    while(t--){

        mark=0;
        Amark = 0;
        Bmark = 0;

        memset(A, '0', sizeof(A));
        memset(B, '0', sizeof(B));
        memset(C, 0, sizeof(C));
        scanf("%s", A);
        scanf("%s", B);
        lenA = strlen(A);
        lenB = strlen(B);

        if(A[0] == '-'){
            for(i=1;i<lenA;++i)
                A[i-1] = A[i];
            A[i-1]= '';
            A[i] = '0';
            Amark = 1;
            lenA--;
        }

        if(B[0] == '-'){
            for(i=1;i<lenB;++i)
                B[i-1] = B[i];
            B[i-1] = '';
            B[i] = '0';
            Bmark = 1;
            lenB--;
        }
        revstr(A,lenA);
        revstr(B,lenB);
        A[lenA] = '';
        B[lenB] = '';
        
        for(i=0;i<lenB;++i){
            for(j=0;j<lenA;++j){
                C[j+i]+=(B[i]-'0')*(A[j]-'0');
            }    
        }
        len = lenA + lenB;
        for(i=0;i<len;++i){
            if(C[i] > 9){
                C[i+1]+=C[i]/10;
                C[i] %= 10;
            }
        }
         while(!C[len-1]){
                 len--;
         }
         //printf("len = %d
", len);
         if(len == 0){ printf("0
"); continue;}
         if(len > -1 && Amark != Bmark)
             putchar('-');
        for(i=len-1;i>=0;i--)
            printf("%d", C[i]);
        
        printf("
");
    }

    return 0;
}