Describe the Painting LeetCode solution in Java

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