Course Schedule III

class Solution {
public:
    int scheduleCourse(vector<vector<int>>& courses) {
        if(courses.size() <= 0) return 0;

        sort(courses.begin(), courses.end(), [](const vector<int>& a, vector<int>& b) {

            return a[1] < b[1];

        });

        priority_queue<int> q;

        int sum = 0;

        for(auto i : courses) {

            sum += i[0];

            q.push(i[0]);

            if(sum > i[1]) {

                sum -= q.top();

                q.pop();

            }

        }

        return q.size();
    }
};