关于 g++ -O2

bool madd(int l, int r, int v)
{
    while (1) {
        bool f = 0;
        for (int i = l; i <= r; i++) {
            a[i] += v;
            // cout << a[i] << endl;
            auto find_iter = m42.find(a[i]);
            if (find_iter != m42.end()) {
                // cout  << i<< "!";
                f = 1;
            }
        }
        if(!f){
            break;
        }
    }
}