DescribeThePainting.java

class Solution {
    //class for segments 
    class Seg{
        int val,end;
        int color;
        boolean isStart;
        public Seg(int val,int end,int color, boolean isStart){
            this.val = val;
            this.end = end;
            this.color = color;
            this.isStart = isStart; 
        }
        public String toString(){
            return "[" + val+" "+end+" "+color+" "+isStart+"]";
        }
    }
    public List<List<Long>> splitPainting(int[][] segments) {
        List<List<Long>> res = new ArrayList();
        
        List<Seg> list = new ArrayList();
        
        //making a list of segments
        for(int[] segment : segments){
            list.add(new Seg(segment[0],segment[1],segment[2],true));
            list.add(new Seg(segment[1],segment[1],segment[2],false));            
        }
        
        //Sorting the segments
        Collections.sort(list,(a,b)->{return a.val-b.val;});
        
        //System.out.println(list);
        
        //Iterating over list to combine the elements
        for(Seg curr: list){
            int len = res.size();
            if(curr.isStart){
                //if the segment is starting there could be three ways 
                if(res.size()>0 && res.get(len-1).get(0)==curr.val){
                    //if starting point of two things is same
                    List<Long> temp = res.get(len-1);
                    temp.set(1,Math.max(temp.get(1),curr.end));
                    temp.set(2,(long)(temp.get(2)+curr.color));
                }else if(res.size()>0 && res.get(len-1).get(1)>curr.val){
                    //if there is a start in between create a new segment of different color 
                    List<Long> prev = res.get(len-1);
                    prev.set(1,(long)curr.val);
                    List<Long> temp = new ArrayList();
                    temp.add((long)curr.val); temp.add((long)curr.end); temp.add((long)(prev.get(2)+curr.color));
                    res.add(temp);
                }else{
                    //Add a new value if nothing is present in result
                    List<Long> temp = new ArrayList();
                    temp.add((long)curr.val); temp.add((long)curr.end); temp.add((long)curr.color);
                    res.add(temp);
                }
            }else{
                if(res.size()>0 && res.get(len-1).get(0)==curr.val){
                    //if ending point of 2 segments is same
                    Long prevColor = res.get(len-1).get(2);
                    res.get(len-1).set(2,(long)(prevColor-curr.color));
                }
                else if(res.size()>0 && res.get(len-1).get(1)>curr.val){
                    //if there is a ending in between create a new segment of different color 
                    Long prevColor = res.get(len-1).get(2);
                    Long prevEnd = res.get(len-1).get(1);
                    res.get(len-1).set(1,(long)curr.val);
                    
                    List<Long> temp = new ArrayList();
                    temp.add((long)curr.val); temp.add((long)prevEnd); temp.add((long)(prevColor-curr.color));
                    res.add(temp);
                }
            }
            //System.out.println(res+" "+curr);
            
        }
        //System.out.println(res);
        return res; 
        
    }
}