g1201_1300.s1254_number_of_closed_islands.Solution.kt Maven / Gradle / Ivy
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Kotlin-based LeetCode algorithm problem solutions, regularly updated
package g1201_1300.s1254_number_of_closed_islands
// #Medium #Array #Depth_First_Search #Breadth_First_Search #Matrix #Union_Find
// #Graph_Theory_I_Day_2_Matrix_Related_Problems
// #2023_06_07_Time_177_ms_(89.47%)_Space_36.7_MB_(81.58%)
class Solution {
private var rows = 0
private var cols = 0
private var isLand = false
fun closedIsland(grid: Array): Int {
rows = grid.size
cols = grid[0].size
var result = 0
for (r in 0 until rows) {
for (c in 0 until cols) {
if (grid[r][c] == 0) {
isLand = true
dfs(grid, r, c)
if (isLand) {
result++
}
}
}
}
return result
}
private fun dfs(grid: Array, r: Int, c: Int) {
if (r == 0 || c == 0 || r == rows - 1 || c == cols - 1) {
isLand = false
}
grid[r][c] = 'k'.code
if (r > 0 && grid[r - 1][c] == 0) {
dfs(grid, r - 1, c)
}
if (c > 0 && grid[r][c - 1] == 0) {
dfs(grid, r, c - 1)
}
if (r < rows - 1 && grid[r + 1][c] == 0) {
dfs(grid, r + 1, c)
}
if (c < cols - 1 && grid[r][c + 1] == 0) {
dfs(grid, r, c + 1)
}
}
}