Leetcode: Smallest Rectangle Enclosing Black Pixels

Smallest Rectangle Enclosing Black Pixels



Similar Problems:


An image is represented by a binary matrix with 0 as a white pixel and 1 as a black pixel. The black pixels are connected, i.e., there is only one black region. Pixels are connected horizontally and vertically. Given the location (x, y) of one of the black pixels, return the area of the smallest (axis-aligned) rectangle that encloses all black pixels.

Example:

Input:
[
  "0010",
  "0110",
  "0100"
]
and x = 0, y = 2

Output: 6

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.


  • Solution: dfs island issues

Similar Problems:

// Blog link: https://code.dennyzhang.com/smallest-rectangle-enclosing-black-pixels
// Basic Ideas: dfs
//  region: (max_x-min_x+1)*(max_y-min_y+1)
// Complexity: Time O(n*m), Space O(1)

var min_x, max_x, min_y, max_y int
func dfs(image [][]byte, x int, y int) {
    if x<0 || x>=len(image) || y<0 || y>=len(image[0]) { return }
    if image[x][y] != '1' { return }
    image[x][y] = '2'
    if x<min_x { min_x = x }
    if x>max_x { max_x = x }
    if y<min_y { min_y = y }
    if y>max_y { max_y = y }
    dfs(image, x+1, y)
    dfs(image, x-1, y)
    dfs(image, x, y+1)
    dfs(image, x, y-1)
}
func minArea(image [][]byte, x int, y int) int {
    if len(image) == 0 { return 0 }
    min_x, max_x = x, x
    min_y, max_y = y, y
    dfs(image, x, y)
    return (max_x-min_x+1)*(max_y-min_y+1)
}
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