高精度运算系列

Add

void add(){
    
    
	memset(a,0,sizeof a);
	memset(b,0,sizeof b);
	memset(c,0,sizeof c);
	int lena=strlen(s1+1);
	int lenb=strlen(s2+1);
	for(int i=1;i<=lena;i++)a[i]=s1[lena-i+1]-'0';
	for(int i=1;i<=lenb;i++)b[i]=s2[lenb-i+1]-'0';
	lenc=max(lena,lenb);
	for(int i=1;i<=lenc;i++){
    
    
		c[i]=c[i]+a[i]+b[i];
		c[i+1]+=c[i]/10;
		c[i]%=10;
	}
	while(c[lenc+1]>0)lenc++;
}

Compare

int compare(char *s1,char *s2){
    
    
	if(lena>lenb)return 1;
	if(lena<lenb)return 0;
	if(lena==lenb&&strcmp(s1,s2)==1)return 1;
	return 0;
}

Sub

void sub(){
    
    
	flag=0;
	lena=strlen(s1+1);
	lenb=strlen(s2+1);
	lenc=max(lena,lenb);
	if(compare(s1+1,s2+1)==0){
    
    
		for(int i=1;i<=lenc;i++){
    
    
			char c=s1[i];
			s1[i]=s2[i];
			s2[i]=c;
		}
		swap(lena,lenb);
		flag=1;
	}
	for(int i=1;i<=lena;i++)a[i]=s1[lena-i+1]-'0';
	for(int i=1;i<=lenb;i++)b[i]=s2[lenb-i+1]-'0';
	for(int i=1;i<=lenc;i++){
    
    
		c[i]=c[i]+a[i]-b[i];
		if(c[i]<0){
    
    c[i]+=10;c[i+1]-=1;}
	}
	while(c[lenc]==0&&lenc>1)lenc--;
	if(flag==1&&c[lenc]!=0)printf("-");
}

Mul

void mul(){
    
    
	lena=strlen(s1+1);
	lenb=strlen(s2+1);
	lenc=lena+lenb-1;
	for(int i=1;i<=lena;i++)a[i]=s1[lena-i+1]-'0';
	for(int i=1;i<=lenb;i++)b[i]=s2[lenb-i+1]-'0';
	for(int i=1;i<=lena;i++){
    
    
		for(int j=1;j<=lenb;j++){
    
    
			c[i+j-1]+=a[i]*b[j];
			c[i+j]+=c[i+j-1]/10;
			c[i+j-1]%=10;
		}
	}
	while(c[lenc+1]>0)lenc++;
	while(c[lenc]==0&&lenc>1)lenc--;
}

大数除法和取余

const int maxn=1000+7;
char s1[maxn],s2[maxn];
int a[maxn],b[maxn],z[maxn];
int lena,lenb,lenbb,len;

int compare(){
    
    
	if(lena>lenb)return 1;
	if(lena<lenb)return -1;
	if(lena==lenb){
    
    
		for(int i=lena;i>0;i--){
    
    
			if(a[i]>b[i])return 1;
			if(a[i]<b[i])return -1;
		}
	}
	return 0;
}

void sub(){
    
    
	for(int i=1;i<=lena;i++){
    
    
		a[i]=a[i]-b[i];
		if(a[i]<0){
    
    
			a[i]+=10;
			a[i+1]--;
		}
	}
    while(a[lena]==0&&lena>1)lena--;
}

int main(){
    
    
	int T;
	scanf("%d",&T);
	while(T--){
    
    
		int flag;
		memset(a,0,sizeof a);
		memset(b,0,sizeof b);
		memset(z,0,sizeof z);
		scanf("%s",s1+1);
		scanf("%s",s2+1);
		lena=strlen(s1+1);
		lenb=strlen(s2+1);
		len=lena-lenb;
		lenbb=lenb;
		for(int i=1;i<=lena;i++)a[i]=s1[lena-i+1]-'0';
		for(int i=1;i<=lenb;i++)b[i]=s2[lenb-i+1]-'0';
		if(compare()<0){
    
    
			printf("%s\n",s1+1);
			printf("0\n");
			continue;
		}
		for(int i=lena;i>0;i--){
    
    
			if(i>len)b[i]=b[i-len];
			else b[i]=0;
		}
		lenb=lena;
		for(int i=len+1;i>0;i--){
    
    //除数最多有len+1位
			while((flag=compare())>=0&&lenb>=lenbb){
    
    
				sub();
				z[i]++;
			}
			if(flag==-1){
    
    
				for(int i=1;i<lenb;i++)b[i]=b[i+1];
				b[lenb]=0;
				lenb--;
			}
		}
		for(int i=len+1;i>0;i--){
    
    
		if(z[i]==0)len--;
		else break;
	}
		for(int i=len+1;i>0;i--)
		printf("%d",z[i]);
		printf("\n");
		for(int i=lena;i>0;i--)
		printf("%d",a[i]);
		printf("\n");
	}
	
	return 0;
}

最后记住随机应变