高精度计算基础

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<string.h>
using namespace std;
char a[105];
char sum[105];
void Reverse(char s[],int len){
    for(int i=0;i<len/2;i++){
        char temp=s[i];
        s[i]=s[len-i-1];
        s[len-i-1]=temp;
    }
}
int main(){
    int maxx;
    scanf("%s",sum);
    maxx=strlen(sum);
    Reverse(sum,maxx);
    while(scanf("%s",a)!=EOF&&a[0]!=‘0‘){
        int len=strlen(a);
        Reverse(a,len);
        //cout<<a<<"len"<<len<<maxx<<endl;
        int k;
        int sumlen=strlen(sum);
        maxx=max(sumlen,len);
        //cout<<maxx<<endl;
        for(int i=0;i<maxx;i++){
                int sums;
            if(sum[i]==0) sums=a[i]-‘0‘;
            else if(a[i]==0) sums=sum[i]-‘0‘;
            else sums=a[i]+sum[i]-2*‘0‘;
            //cout<<sums<<endl;
            k=i;
            while(sums!=0){
                if(k==i)   sum[k]=sums%10+‘0‘;
                else if(sum[k]==0)sum[k]=sums%10+‘0‘;
                else sum[k]+=sums%10;
                sums/=10;
                k++;
            }

        }
        if(k>maxx) sum[k]=‘\0‘;
        else sum[maxx]=‘\0‘;
    }
    int lens=strlen(sum);
    for(int j=lens-1;j>=0;j--){
        printf("%c",sum[j]);
    }
    cout<<endl;
return 0;
}

#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
int a[505],b[505],c[505],sum[505];
char str1[505],str2[505];

int main(){
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
    while(scanf("%s",str1)!=EOF){
            memset(sum,0,sizeof(sum));
        int len1=strlen(str1);
        for(int i=0;i<len1;i++){
            a[len1-i-1]=str1[i]-‘0‘;
        }
        scanf("%s",str2);
        if(str1[0]==‘0‘||str2[0]==‘0‘){
            cout<<0<<endl;
            continue;
        }
        int len2=strlen(str2);
        for(int i=0;i<len2;i++){
            b[len2-i-1]=str2[i]-‘0‘;
        }
        int k;
        for(int i=0;i<len1;i++){
            for(int j=0;j<len2;j++){
                int sums=a[i]*b[j];
                 k=j+i;
                do{
                    sum[k]+=sums%10;
                    sums/=10;
                    k++;
                }while(sums!=0);
            }
        }
        int w;
        for(int i=0;i<k;i++){
               w=i;
               int sumss=sum[i];
                do{
                        if(w==i)sum[w]=sumss%10;
                    else sum[w]+=sumss%10;
                    sumss/=10;
                    w++;
                }while(sumss!=0);
        }
        for(int i=w-1;i>=0;i--){
            printf("%d",sum[i]);
        }
        cout<<endl;
    }
return 0;
}