【BZOJ】1754: [Usaco2005 qua]Bull Math

【算法】高精度乘法

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int maxn=;

char s1[maxn],s2[maxn];
int a[maxn],b[maxn],c[maxn],lena,lenb,lenc;
int main(){
    scanf("%s%s",s1,s2);
    lena=strlen(s1);lenb=strlen(s2);
    for(int i=;i<lena;i++)a[lena-i]=s1[i]-'';
    for(int i=;i<lenb;i++)b[lenb-i]=s2[i]-'';
    for(int i=;i<=lena;i++){
        int x=;
        for(int j=;j<=lenb;j++){
            x=a[i]*b[j]+x+c[i+j-];
            c[i+j-]=x%;
            x/=;
        }
        c[i+lenb]=x;
    }
    lenc=lena+lenb;
    while(lenc>&&!c[lenc])lenc--;
    for(int i=lenc;i>=;i--)printf("%d",c[i]);
    return ;
}