const int part = 5;
int partLength = (int)ceil(1000 / (float)part);
for (int i = 0;i<partLength ;i++){
    class a1 = array[i];
    if (a1.condition == condition) break;

    int i2 = i + partLength;
    class a2 = array[i2];
    if (a2.condition == condition) break;

    int i3 = i2 + partLength;
    class a3 = array[i3];
    if (a3.condition == condition) break;

    int i4 = i3 + partLength;
    class a4 = array[i4];
    if (a4.condition == condition) break;

    int i5 = i4 + partLength;
    if (i5 < 1000) {
        class a5 = array[i5];
        if (a5.condition == condition) break;
    }
}