int totalTime=0 , coursesN=0; 
    public int scheduleCourse(int[][] courses) {
        
        ArrayList<Integer> durations = new ArrayList<>();
        
        if(courses.length==0)return 0 ;
        
        for(int i=0 ; i<courses.length ; i++){
            
            if ( courses[i][0] <= courses[i][1] ){
                
                
                if(totalTime+courses[i][0] <= courses[i][1]){
                    coursesN++;
                    totalTime+=courses[i][0];
                    durations.add(courses[i][0]);
                }else{
                    int maxdur = Collections.max(durations) ;
                    totalTime-= maxdur ;
                    totalTime+=Math.min(maxdur , courses[i][0] );
                }
            } 
            
        }return coursesN;