BuildingOutline.java

import java.util.*;

public class Solution {

  class HashHeap {
    ArrayList<Integer> heap;
    String mode;
    int size_t;
    HashMap<Integer, Node> hash;

    class Node {
      public Integer id;
      public Integer num;

      Node(Node now) {
        id = now.id;
        num = now.num;
      }

      Node(Integer first, Integer second) {

        this.id = first;
        this.num = second;
      }
    }

    public HashHeap(String mod) {
      // TODO Auto-generated constructor stub
      heap = new ArrayList<Integer>();
      mode = mod;
      hash = new HashMap<Integer, Node>();
      size_t = 0;
    }

    public int peek() {
      return heap.get(0);
    }

    public int size() {
      return size_t;
    }

    public Boolean isEmpty() {
      return (heap.size() == 0);
    }

    int parent(int id) {
      if (id == 0) {
        return -1;
      }
      return (id - 1) / 2;
    }

    int lson(int id) {
      return id * 2 + 1;
    }

    int rson(int id) {
      return id * 2 + 2;
    }

    boolean comparesmall(int a, int b) {
      if (a <= b) {
        if (mode == "min")
          return true;
        else
          return false;
      } else {
        if (mode == "min")
          return false;
        else
          return true;
      }

    }

    void swap(int idA, int idB) {
      int valA = heap.get(idA);
      int valB = heap.get(idB);

      int numA = hash.get(valA).num;
      int numB = hash.get(valB).num;
      hash.put(valB, new Node(idA, numB));
      hash.put(valA, new Node(idB, numA));
      heap.set(idA, valB);
      heap.set(idB, valA);
    }

    public Integer poll() {
      size_t--;
      Integer now = heap.get(0);
      Node hashnow = hash.get(now);
      if (hashnow.num == 1) {
        swap(0, heap.size() - 1);
        hash.remove(now);
        heap.remove(heap.size() - 1);
        if (heap.size() > 0) {
          siftdown(0);
        }
      } else {
        hash.put(now, new Node(0, hashnow.num - 1));
      }
      return now;
    }

    public void add(int now) {
      size_t++;
      if (hash.containsKey(now)) {
        Node hashnow = hash.get(now);
        hash.put(now, new Node(hashnow.id, hashnow.num + 1));

      } else {
        heap.add(now);
        hash.put(now, new Node(heap.size() - 1, 1));
      }

      siftup(heap.size() - 1);
    }

    public void delete(int now) {
      size_t--;
      Node hashnow = hash.get(now);
      int id = hashnow.id;
      int num = hashnow.num;
      if (hashnow.num == 1) {

        swap(id, heap.size() - 1);
        hash.remove(now);
        heap.remove(heap.size() - 1);
        if (heap.size() > id) {
          siftup(id);
          siftdown(id);
        }
      } else {
        hash.put(now, new Node(id, num - 1));
      }
    }

    void siftup(int id) {
      while (parent(id) > -1) {
        int parentId = parent(id);
        if (comparesmall(heap.get(parentId), heap.get(id)) == true) {
          break;
        } else {
          swap(id, parentId);
        }
        id = parentId;
      }
    }

    void siftdown(int id) {
      while (lson(id) < heap.size()) {
        int leftId = lson(id);
        int rightId = rson(id);
        int son;
        if (rightId >= heap.size()
            || (comparesmall(heap.get(leftId), heap.get(rightId)) == true)) {
          son = leftId;
        } else {
          son = rightId;
        }
        if (comparesmall(heap.get(id), heap.get(son)) == true) {
          break;
        } else {
          swap(id, son);
        }
        id = son;
      }
    }
  }

  class Edge {
    int pos;
    int height;
    boolean isStart;

    public Edge(int pos, int height, boolean isStart) {
      this.pos = pos;
      this.height = height;
      this.isStart = isStart;
    }

  }

  class EdgeComparator implements Comparator<Edge> {
    @Override
    public int compare(Edge arg1, Edge arg2) {
      Edge l1 = (Edge) arg1;
      Edge l2 = (Edge) arg2;
      if (l1.pos != l2.pos)
        return compareInteger(l1.pos, l2.pos);
      if (l1.isStart && l2.isStart) {
        return compareInteger(l2.height, l1.height);
      }
      if (!l1.isStart && !l2.isStart) {
        return compareInteger(l1.height, l2.height);
      }
      return l1.isStart ? -1 : 1;
    }

    int compareInteger(int a, int b) {
      return a <= b ? -1 : 1;
    }
  }

  List<List<Integer>> output(List<List<Integer>> res) {
    List<List<Integer>> ans = new ArrayList<List<Integer>>();
    if (res.size() > 0) {
      int pre = res.get(0).get(0);
      int height = res.get(0).get(1);
      for (int i = 1; i < res.size(); i++) {
        List<Integer> now = new ArrayList<Integer>();
        int id = res.get(i).get(0);
        if (height > 0) {
          now.add(pre);
          now.add(id);
          now.add(height);
          ans.add(now);
        }
        pre = id;
        height = res.get(i).get(1);
      }
    }
    return ans;
  }

  public List<List<Integer>> buildingOutline(int[][] buildings) {
    // write your code here
    List<List<Integer>> res = new ArrayList<List<Integer>>();

    if (buildings == null || buildings.length == 0
        || buildings[0].length == 0) {
      return res;
    }
    ArrayList<Edge> edges = new ArrayList<Edge>();
    for (int[] building : buildings) {
      Edge startEdge = new Edge(building[0], building[2], true);
      edges.add(startEdge);
      Edge endEdge = new Edge(building[1], building[2], false);
      edges.add(endEdge);
    }
    Collections.sort(edges, new EdgeComparator());

    HashHeap heap = new HashHeap("max");

    List<Integer> now = null;
    for (Edge edge : edges) {
      if (edge.isStart) {
        if (heap.isEmpty() || edge.height > heap.peek()) {
          now = new ArrayList<Integer>(Arrays.asList(edge.pos,
              edge.height));
          res.add(now);
        }
        heap.add(edge.height);
      } else {
        heap.delete(edge.height);
        if (heap.isEmpty() || edge.height > heap.peek()) {
          if (heap.isEmpty()) {
            now = new ArrayList<Integer>(Arrays.asList(edge.pos, 0));
          } else {
            now = new ArrayList<Integer>(Arrays.asList(edge.pos,
                heap.peek()));
          }
          res.add(now);
        }
      }
    }
    return output(res);
  }