大佬们帮忙看一下，谢谢啦！

#include<cstdio>
#include<cstring>
#include<iostream>
#define maxn 51
using namespace std;
char rec[maxn],res[maxn][maxn],op[maxn];
int Num1(int x,int y,int i){
	int ss=0;
	for(int k=x;k<=y;++k){
		ss=ss*10+res[i][k]-'0';
	}
	return ss;
}
int main(){
	int n,len,num1,num2,num,cnt1=0,nn;
	scanf("%d\n",&n);
	for(int i=1;i<=n;++i){
		cin.getline(rec,52);
		len=strlen(rec);
		if(rec[0]=='a'||rec[0]=='b'||rec[0]=='c'){
			op[i]=rec[0];
			for(int j=2;j<len;++j){
				if(rec[j]!=' '){
					res[i][j-2]=rec[j];
				}else res[i][j-2]=op[i];
			}
		}else{
			op[i]=op[i-1];
			for(int j=0;j<len;++j){
				if(rec[j]!=' '){
					res[i][j]=rec[j];
				}else res[i][j]=op[i];
			}
		} 	
	} 
	for(int i=1;i<=n;++i){
		len=strlen(res[i]);
		for(int j=0;j<len;++j){
			if(res[i][j]==op[i]){
				num1=Num1(0,j-1,i);
				num2=Num1(j+1,len-1,i);
				cnt1=0;
				switch(op[i]){
					case'a': num=num1+num2; 
							nn=num;
							if(nn==0) cnt1++;
							while(nn){
								cnt1++;
								nn/=10;	
							} 
							printf("%d+%d=%d\n%d\n",num1,num2,num,len+1+cnt1);
							break;
					case'b': num=num1-num2;
							 nn=num;
					         if(nn<0){
					         	nn=(-1)*nn;
					         	cnt1++;
							 }else if(nn==0) cnt1++; 
							while(nn){
								cnt1++;
								nn/=10;	
							} 
							printf("%d-%d=%d\n%d\n",num1,num2,num,len+1+cnt1);
							break;
					case'c': num=num1*num2; 
							 nn=num;
							if(nn==0) cnt1++;
							while(nn){
										cnt1++;
										nn/=10;	
							} 
							printf("%d*%d=%d\n%d\n",num1,num2,num,len+1+cnt1);
							break;
				}
			}
		}	
	}
	return 0;
}