标签：Perfect set get int map2 key rectangles LeetCode Rectangle

Given N axis-aligned rectangles where N > 0, determine if they all together form an exact cover of a rectangular region.

Each rectangle is represented as a bottom-left point and a top-right point. For example, a unit square is represented as [1,1,2,2]. (coordinate of bottom-left point is (1, 1) and top-right point is (2, 2)).


Example 1:

rectangles = [
  [1,1,3,3],
  [3,1,4,2],
  [3,2,4,4],
  [1,3,2,4],
  [2,3,3,4]
]

Return true. All 5 rectangles together form an exact cover of a rectangular region.
 

 

Example 2:

rectangles = [
  [1,1,2,3],
  [1,3,2,4],
  [3,1,4,2],
  [3,2,4,4]
]

Return false. Because there is a gap between the two rectangular regions.
 

 

Example 3:

rectangles = [
  [1,1,3,3],
  [3,1,4,2],
  [1,3,2,4],
  [3,2,4,4]
]

Return false. Because there is a gap in the top center.
 

 

Example 4:

rectangles = [
  [1,1,3,3],
  [3,1,4,2],
  [1,3,2,4],
  [2,2,4,4]
]

Return false. Because two of the rectangles overlap with each other.

class Solution {
    // 1. Exact 4 corners
    // 2. Other shared points must occur evenly (cannot be odd)
    // 3. sum(area) = area of 4 corners enclosed areas
    private String delimiter = ",";
    public boolean isRectangleCover(int[][] rectangles) {
        Map<String, Integer> set = new HashMap<>();
        Map<String, int[]> map2 = new HashMap<>();
        int sum = 0;
        for (int i = 0; i < rectangles.length; i++) {
                sum = sum + (rectangles[i][2] - rectangles[i][0]) * (rectangles[i][3] - rectangles[i][1]);
                // bottom-left
                String blKey = generateKey(rectangles[i][0], rectangles[i][1]);
                if (set.containsKey(blKey)) {
                    map2.remove(blKey);
                }
                else {
                    map2.put(blKey, new int[]{rectangles[i][0], rectangles[i][1]});
                }
                set.put(blKey, set.getOrDefault(blKey, 0) + 1);
                // top-right
                String trKey = generateKey(rectangles[i][2], rectangles[i][3]);
                if (set.containsKey(trKey)) {
                    map2.remove(trKey);
                }
                else {
                    map2.put(trKey, new int[]{rectangles[i][2], rectangles[i][3]});
                }
                set.put(trKey, set.getOrDefault(trKey, 0) + 1);
                //top-left
                String tlKey = generateKey(rectangles[i][0], rectangles[i][3]);
                if (set.containsKey(tlKey)) {
                    map2.remove(tlKey);
                }
                else {
                    map2.put(tlKey, new int[]{rectangles[i][0], rectangles[i][3]});
                }
                set.put(tlKey, set.getOrDefault(tlKey, 0) + 1);
                //bottom-right
                String brKey = generateKey(rectangles[i][2], rectangles[i][1]);
                if (set.containsKey(brKey)) {
                    map2.remove(brKey);
                }
                else {
                    map2.put(brKey, new int[]{rectangles[i][2], rectangles[i][1]});
                }
                set.put(brKey, set.getOrDefault(brKey, 0) + 1);
        }
        if (map2.size() == 4) {
            for (String key: set.keySet()) {
                if (set.get(key) % 2 != 0 && set.get(key) != 1) {
                    return false;
                }
            }
            int maxL = Integer.MIN_VALUE;
            int minL = Integer.MAX_VALUE;
            int maxW = Integer.MIN_VALUE;
            int minW = Integer.MAX_VALUE;
            for (String key : map2.keySet()) {
                if(map2.get(key)[0] > maxL) {
                    maxL = map2.get(key)[0];
                }
                if(map2.get(key)[0] < minL) {
                    minL = map2.get(key)[0];
                }
                if(map2.get(key)[1] > maxW) {
                    maxW = map2.get(key)[1];
                }
                if(map2.get(key)[1] < minW) {
                    minW = map2.get(key)[1];
                }
            }
            System.out.println("Sum: " + sum);
            System.out.println("Area: " + (maxL - minL) * (maxW - minW));
            if(sum == (maxL - minL) * (maxW - minW)) {
                return true;
            }
        }
        return false;
    }
    
    private String generateKey(int i, int j) {
        return Integer.toString(i) + delimiter + Integer.toString(j);
    }
}

标签：Perfect,set,get,int,map2,key,rectangles,LeetCode,Rectangle
来源： https://www.cnblogs.com/incrediblechangshuo/p/14436750.html

本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享；
2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关；
3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关；
4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除；
5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。