包括$+,-,*$操作，适用于非负整数
减法只能大减小
并没有压位
1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 using namespace std; 5 #define N 250002 6 int max(int a,int b){return a>b?a:b;} 7 struct bignum{ 8 int a[N],len; 9 bignum(){memset(a,0,sizeof(a));len=0;} 10 void init(){ 11 static char b[N];scanf("%s",b); 12 len=strlen(b); 13 for(int i=1;i<=len;++i)a[i]=b[len-i]-48; 14 } 15 void print(){ 16 for(int i=len;i>=1;--i) putchar(a[i]+48); 17 } 18 bool operator < (const bignum &tmp) const{ 19 if(len!=tmp.len) return len<tmp.len; 20 for(int i=1;i<=len;++i) 21 if(a[i]!=tmp.a[i]) 22 return a[i]<tmp.a[i]; 23 return 0; 24 } 25 bignum operator + (const bignum &tmp) const{ 26 bignum c; int x=0; 27 c.len=max(len,tmp.len); 28 for(int i=1;i<=c.len;++i){ 29 c.a[i]=a[i]+tmp.a[i]+x; 30 x=c.a[i]/10;c.a[i]%=10; 31 } 32 for(;x;x/=10) c.a[++c.len]=x%10; 33 return c; 34 } 35 bignum operator - (const bignum &tmp) const{ 36 bignum c; c.len=len; 37 for(int i=len;i>=1;--i){ 38 c.a[i]=a[i]-tmp.a[i]; 39 for(int j=i;c.a[j]<0;++j) 40 --c.a[j+1],c.a[j]+=10; 41 while(!c.a[c.len]&&c.len>i) --c.len; 42 }return c; 43 } 44 bignum operator * (const bignum &tmp) const{ 45 bignum c;int x=0; 46 c.len=len+tmp.len-1; 47 for(int i=1,j;i<=len;++i,x=0){ 48 for(j=1;j<=tmp.len;++j){ 49 c.a[i+j-1]+=a[i]*tmp.a[j]+x; 50 x=c.a[i+j-1]/10;c.a[i+j-1]%=10; 51 }c.a[i+j-1]+=x; 52 } 53 for(;c.a[c.len]>9;++c.len) 54 c.a[c.len+1]+=c.a[c.len]/10,c.a[c.len]%=10; 55 while(!c.a[c.len]&&c.len>1) --c.len; 56 return c; 57 } 58 }x,y; 59 int main(){ 60 x.init(); y.init(); 61 x=x+y; 62 //if(x<y) swap(x,y),putchar('-'); 63 //x=x-y; 64 //x=x*y; 65 x.print(); 66 return 0; 67 }