UVa - 11878 - Homework Checker

#include <iostream>
#include <vector>
#include <cmath>
using namespace std;

int main(){
    int a, b, ans, cnt = 0;
    string equation, x, y, answer;
    while(getline(cin, equation)){
        int l = equation.size(), j = 0;
        for(int i = j; i < l; i++){
            if(equation[i] == '+' || equation[i] == '-'){j++;break;}
            x.push_back(equation[i]);j++;
        }
        for(int i = j; i < l; i++){
            if(equation[i] == '='){j++;break;}
            y.push_back(equation[i]);j++;
        }
        for(int i = j; i < l; i++){
            if(equation[i] == '\0'){j++;break;}
            answer.push_back(equation[i]);j++;
        }
        int l1 = x.size(), l2 = y.size(), l3 = answer.size();

        a = x[0] - 48;
        for(int i = 1; i < l1; i++){
            a = (a*10) + (x[i]-48);
        }

        b = y[0] - 48;
        for(int i = 1; i < l2; i++){
            b = (b*10) + (y[i]-48);
        }

        ans = answer[0] - 48;
        for(int i = 1; i < l3; i++){
            ans = (ans*10) + (answer[i]-48);
        }
        int sol;
        for(int i = 0; i < l; i++)
        if(equation[i] == '+'){
            sol = a + b;
            if(sol == ans)cnt++;
            break;
        }
        else if(equation[i] == '-'){
            sol = a - b;
            if(sol == ans)cnt++;
            break;
        }
        x.clear();y.clear();answer.clear();equation.clear();
    }
    cout << cnt << endl;
    return 0;
}