1 #include<cstdio> 2 #include<cstring> 3 using namespace std; 4 const int N = 1001; 5 const int DLEN = 4; 6 const int mod = 10000; 7 int alen, blen; 8 int ans_len; 9 char a1[N], b1[N];10 int a[600], b[600];11 int ans[600];12 13 void BigInt(const char s[], int (&c)[600], int &len){14     memset(c, 0, sizeof(c));15     int L = strlen(s);16     len = L / DLEN;17     if(L%DLEN) len++;18     int cnt = 0;19     for(int i = L-1; i >= 0 ; i -= DLEN){20         int k = i - DLEN + 1;21         if(k < 0) k = 0;22         int t = 0;23         for(int j = k; j <= i; ++j)24             t = t * 10 + s[j] - ‘0‘;25         c[cnt++] = t;26     }27 }28 void multi(){29     int i, j;30     for(i = 0; i < alen; ++i){31         int up = 0;32         for(j = 0; j < blen; ++j){33             int t = a[i] * b[j] + ans[i+j] + up;34             up = t / mod;35             ans[i+j] = t % mod;36         }37         if(up != 0)38             ans[i+j] = up;39     }40     ans_len = alen + blen;41     while(ans[ans_len-1] == 0 && ans_len > 1)42         ans_len--;43 44     printf("%d", ans[ans_len-1]);45     for(i = ans_len-2; i >= 0; i--)46         printf("%04d", ans[i]);47     puts("");48 }49 int main(){50     scanf("%s%s", a1, b1);51     BigInt(a1, a, alen);52     BigInt(b1, b, blen);53     multi();54     return 0;55 }