1046. Last Stone Weight

class Solution {
public:
    int lastStoneWeight(vector<int>& stones) {
        priority_queue<int> pq;
        
        for(int x : stones) pq.push(x);
        
        while(pq.size() > 1) {
            int a = pq.top(); pq.pop();
            int b = pq.top(); pq.pop();
            
            if(b != a) pq.push(a - b);
        }
        
        return pq.empty() ? 0 : pq.top();
    }
};