391. 完美矩形

https://leetcode-cn.com/problems/perfect-rectangle/

• 提交时间:2021-11-16 03:07:26
• 执行用时：64 ms, 在所有 Go 提交中击败了40.63%的用户
• 内存消耗：8.1 MB, 在所有 Go 提交中击败了34.38%的用户
• 通过测试用例：47 / 47

type pos struct {
    x int
    y int
}

func isRectangleCover(rectangles [][]int) bool {

    //总面积
    areaTotal := 0
    //记录最外层顶点位置
    pointVertexMax := rectangles[0]
    //记录顶点map
    pointVertexMap := make(map[pos]int)
    //遍历所有矩形
    for _, recItem := range rectangles {
        //统计面积
        areaTotal += (recItem[2] - recItem[0]) * (recItem[3] - recItem[1])
        //左下顶点
        if recItem[0] < pointVertexMax[0] || recItem[1] < pointVertexMax[1] {
            pointVertexMax[0] = recItem[0]
            pointVertexMax[1] = recItem[1]
        }
        //右上顶点
        if recItem[2] > pointVertexMax[2] || recItem[3] > pointVertexMax[3] {
            pointVertexMax[2] = recItem[2]
            pointVertexMax[3] = recItem[3]
        }
        pointVertexMap[pos{recItem[0], recItem[1]}]++
        pointVertexMap[pos{recItem[2], recItem[3]}]++
        pointVertexMap[pos{recItem[2], recItem[1]}]++
        pointVertexMap[pos{recItem[0], recItem[3]}]++
    }

    //fmt.Printf("pointVertexMap,%+v,areaTotal:%+v, pointMax:%+v\n", pointVertexMap, areaTotal, pointVertexMax)
    //判断面积是否吻合
    if (pointVertexMax[2]-pointVertexMax[0])*(pointVertexMax[3]-pointVertexMax[1]) != areaTotal {
        return false
    }
    pointVertexLog := 0
    //判断同一位置顶点数量 除了最外部顶点,应该只能是2或者4
    for posItem, pointVertexCount := range pointVertexMap {
        if pointVertexCount != 2 && pointVertexCount != 4 {
            if pointVertexCount == 1 {
                pointVertexLog++
            }
            //不是顶点
            if posItem.x != pointVertexMax[0] && posItem.x != pointVertexMax[2] {
                return false
            }
            if posItem.y != pointVertexMax[1] && posItem.y != pointVertexMax[3] {
                return false
            }
        }
    }
    return pointVertexLog == 4
}