题解 | #A+B#

#include <iostream>
using namespace std;

struct bign {
    int data[10] ;
    int len;
    int fuhao;
    bign() {
        len = 0;
        fuhao = 0;
        for (int i = 0; i < 10; ++i) {
            data[i] = 0;
        }
    }

};
bign to_b(string str) {
    int len = str.length();
    bign b1;
    for (int i = 0; i < len; i++) {
        if (str[len - i - 1] >= '0' && str[len - i - 1] <= '9') {
            b1.data[b1.len++] = str[len - i - 1] - '0';
        }
    }
    if (str[0] == '-') b1.fuhao = 1;
    return b1;
}

bign add_b(bign b1, bign b2) {
    int carry = 0;
    bign b3;
    for (int i = 0; i < b1.len || i < b2.len; i++) {
        int a = b1.data[i] + b2.data[i] + carry;
        b3.data[b3.len++] = a % 10;
        carry = a / 10;

    }
    if (carry != 0) {
        b3.data[b3.len++] = carry;
    }
    return b3;
}

bool cmp(bign b1, bign b2) {//b1>b2为真
    if(b1.len<b2.len){
        return false;
    }
    if(b1.len==b2.len){
        for(int i=b1.len-1;i>=0;i--){
            
            if(b1.data[i]>b2.data[i]){
                return true;
            }else if(b1.data[i]<b2.data[i])
            {
            	return false;
			}
        }
    }
    return true;
   
}

bign sub_b(bign b1,bign b2){
    int carry=0;
    bign b3;
    for(int i=0;i<b1.len||i<b2.len;i++){
        int a=b1.data[i]-b2.data[i]-carry;
        if(a<0){
            carry=1;
            b3.data[b3.len++]=a+10;//不要忘了修改长度
        }else{
            b3.data[b3.len++]=a;
            carry = 0;
        }
    }
    while(b3.data[b3.len-1]==0){
        b3.len--;
    }
    return b3;
}
int main() {
    string str1, str2;
    while (cin >> str1 >> str2) { // 注意 while 处理多个 case
        bign b1 = to_b(str1);
        bign b2 = to_b(str2);
        bign b3;
        if (b1.fuhao == 1 && b2.fuhao == 1) {
            b3 = add_b(b1, b2);
            cout << "-";
        } else if (b1.fuhao == 0 && b2.fuhao == 0) {
            b3 = add_b(b1, b2);
        } else if (b1.fuhao == 1 && b2.fuhao == 0) {
            bool dx = cmp(b1, b2);
            if (dx) { //dxtrue表示b1>b2,shuchufuhao
                cout << "-";
                b3 = sub_b(b1, b2);

            } else {
                b3 = sub_b(b2, b1);
            }
        } else {
            bool dx = cmp(b2, b1);
            if (dx) { //dxtrue表示b2>b1,shuchufuhao
                cout << "-";
                b3 = sub_b(b2, b1);

            } else {
                b3 = sub_b(b1, b2);
            }
        }
        for (int i = b3.len - 1; i >= 0; i--) {
            cout << b3.data[i];
            
        }
        cout<<endl;

    }
}
// 64 位输出请用 printf("%lld")

哭了，改了好多遍终于对了！！