About custom comparison methods of classes and custom methods of sort functions

The title of a ladder ：21 Year of
L2-3 Inventory code base (25 branch )
The code borrows from the boss ：
https://blog.csdn.net/weixin_45962741/article/details/116229100

Here, I want to summarize and record the custom comparison methods and sort Function custom comparison method

Class ：

struct Node
{
    
	vector<int>v;
	int count;
	bool operator<(const Node& vv)const {
    
		if (vv.count == count) return v < vv.v;
		else return count > vv.count;
	}
};

Apply overload mechanism , change < perhaps >, Change his ranking basis
stay operator Redefine comparison rules in , It can be applied to map,set And so on

sort Function's custom comparison method

bool cmp(Node a, Node b) {
    
	if (a.count == b.count) return a.v < b.v;
	else return a.count > b.count;
}

Create a bool function , Inner structure comparison method , It can be applied to sort Function to sort classes by themselves .

	sort(node.begin(), node.end(),cmp);

take cmp Attached to sort At the back of .