preface

Using unordered_ The compilation error caused by the set container is a call to the implicitly deleted default constructor.

	unordered_map<pair<int, int>>
	unordered_set<pair<int, int>>

reason

unordered_ Map and unordered_ Set uses the default STD:: hash to calculate the key, but STD:: hash cannot handle the pair type.

Solution:

Use map, set instead

Custom hash function