c++ comparing all elements of a vector

I'm trying to create a C++ function which controls if N rectangles are collisioning. The N rectangles are in a std::vector. The idea is to compare every element of the vector with others (only one time) to verify if there are collisions. I already implemented code to do this, but I am looking for a better, cleaner and more elegant way (I'm a C++ newbie). My code is:

bool areCollisioningNRectangles(std::vector<Rectangle> rect) {
    const unsigned long size = rect.size();

    for (int i = 0; i < size - 1; i++) {
        for (int j = i + 1; j < size; j++) {
            if (areCollisioningTwoRectangles(rect[i], rect[j])) {
                return true;
            }
        }
        return false;
    }
}