[Swift]LeetCode391. 完美矩形 | Perfect Rectangle

原文地址：https://www.cnblogs.com/strengthen/p/10299478.html 

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.

---

我们有 N 个与坐标轴对齐的矩形, 其中 N > 0, 判断它们是否能精确地覆盖一个矩形区域。

每个矩形用左下角的点和右上角的点的坐标来表示。例如， 一个单位正方形可以表示为 [1,1,2,2]。 ( 左下角的点的坐标为 (1, 1) 以及右上角的点的坐标为 (2, 2) )。

示例 1:

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

返回 true。5个矩形一起可以精确地覆盖一个矩形区域。 

示例 2:

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

返回 false。两个矩形之间有间隔，无法覆盖成一个矩形。

示例 3:

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

返回 false。图形顶端留有间隔，无法覆盖成一个矩形。

示例 4:

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

返回 false。因为中间有相交区域，虽然形成了矩形，但不是精确覆盖。 

---

524ms

class Solution {
    func isRectangleCover(_ rectangles: [[Int]]) -> Bool {
        var st:Set<String> = Set<String>()
        var min_x = Int.max
        var min_y = Int.max
        var max_x = Int.min
        var max_y = Int.min
        var area:Int = 0
        for rect in rectangles
        {
            min_x = min(min_x, rect[0])
            min_y = min(min_y, rect[1])
            max_x = max(max_x, rect[2])
            max_y = max(max_y, rect[3])
            area += (rect[2] - rect[0]) * (rect[3] - rect[1])
            var s1:String = String(rect[0]) + "_" + String(rect[1]) // bottom-left
            var s2:String = String(rect[0]) + "_" + String(rect[3]) // top-left
            var s3:String = String(rect[2]) + "_" + String(rect[3]) // top-right
            var s4:String = String(rect[2]) + "_" + String(rect[1]) // bottom-right
            if st.contains(s1) {st.remove(s1)}
            else {st.insert(s1)}
            if st.contains(s2) {st.remove(s2)}
            else {st.insert(s2)}
            if st.contains(s3) {st.remove(s3)}
            else {st.insert(s3)}
            if st.contains(s4) {st.remove(s4)}
            else {st.insert(s4)}            
        }
        var t1:String = String(min_x) + "_" + String(min_y)
        var t2:String = String(min_x) + "_" + String(max_y)
        var t3:String = String(max_x) + "_" + String(max_y)
        var t4:String = String(max_x) + "_" + String(min_y)
        if !st.contains(t1) || !st.contains(t2) || !st.contains(t3) || !st.contains(t4) || st.count != 4
        {
            return false
        }
        return area == (max_x - min_x) * (max_y - min_y)
    }
}

---

1496ms

class Solution {
            func isRectangleCover(_ rectangles: [[Int]]) -> Bool {
        var dic = Dictionary<String,Int>()
        var commenDic = Dictionary<String,Int>()
        //计算面积（排除覆盖）
        var minX = rectangles[0][0]
        var minY = rectangles[0][1]
        var maxX = rectangles[0][2]
        var maxY = rectangles[0][3]
        var area:Int = 0
        //计算角的个数
        for i in rectangles{
            if i[0] < minX {
                minX = i[0]
            }
            if i[1] < minY {
                minY = i[1]
            }
            if i[2] > maxX {
                maxX = i[2]
            }
            if i[3] > maxY {
                maxY = i[3]
            }
            area += (i[2]-i[0]) * (i[3]-i[1])

            let p1 = String(i[0])+","+String(i[1])
            let p2 = String(i[0])+","+String(i[3])

            let p3 = String(i[2])+","+String(i[3])
            let p4 = String(i[2])+","+String(i[1])
            let pArr = [p1,p2,p3,p4]
            for p in pArr{
                if let _ = dic[p]{
                    dic[p] = nil
                }else{
                    dic[p] = 1
                }
            }
            //去除遮挡
            let p11 = p1 + ",1"
            let p21 = p2 + ",2"
            let p31 = p3 + ",3"
            let p41 = p4 + ",4"
            let pArr2 = [p11,p21,p31,p41]
            for p in pArr2{
                if let _ = commenDic[p]{
                    return false
                }else{
                    commenDic[p] = 1
                }
            }
        }
        if dic.count != 4{
            return false
        }
        if area != (maxY - minY) * (maxX - minX){
            return false
        }
        return true
    }
}