大数乘法。
代码如下：
1 #include<stdio.h> 2 #include<string.h> 3 4 void func(char a[]) 5 { 6 int i, len=strlen(a); 7 char t; 8 for (i=0; i<len/2; i++) 9 { 10 t=a[i]; 11 a[i]=a[len-i-1]; 12 a[len-i-1]=t; 13 } 14 } 15 16 int main() 17 { 18 int alen, blen, s, len, i, j; 19 char a[260], b[260], r[1000], t; 20 while(scanf("%s%s%*c", a, b)==2) 21 { 22 memset(r, 0, sizeof(r)); 23 alen=strlen(a); 24 blen=strlen(b); 25 func(a); 26 func(b); 27 for (i=0; i<alen; i++) 28 { 29 s=0; 30 for (j=0; j<blen; j++) 31 { 32 t=r[i+j]+(a[i]-'0')*(b[j]-'0')+s; 33 s=t/10; 34 r[i+j]=t%10; 35 } 36 if (s > 0) 37 r[i+j]+=s; 38 } 39 if (s > 0) 40 len=alen+blen; 41 else 42 len=alen+blen-1; 43 if (strcmp(a, "0") == 0 || strcmp(b, "0") == 0) 44 len = 1; 45 for (i=len-1; i>=0; i--) 46 printf("%c", r[i]+'0'); 47 printf("\n"); 48 } 49 return 0; 50 }
