number_of_isalands
number_of_isalands.go 源码
package leetcode
//岛屿数量
//深度优先的思路解决
func numIslands1(grid [][]byte) int {
visited, res := make([][]bool, len(grid)), 0
for i := range visited {
visited[i] = make([]bool, len(grid[0]))
}
for i := 0; i < len(grid); i++ {
for j := 0; j < len(grid[0]); j++ {
if grid[i][j] == '1' && !visited[i][j] {
numIslandsHelper(grid, i, j, visited)
res++
}
}
}
return res
}
func numIslandsHelper(grid [][]byte, i, j int, visited [][]bool) {
if i < 0 || j < 0 || i >= len(grid) || j >= len(grid[0]) {
return
}
if visited[i][j] || grid[i][j] == '0' {
return
}
visited[i][j] = true
numIslandsHelper(grid, i-1, j, visited)
numIslandsHelper(grid, i, j-1, visited)
numIslandsHelper(grid, i+1, j, visited)
numIslandsHelper(grid, i, j+1, visited)
}
//广度优先的思路解决
func numIslands2(grid [][]byte) int {
var queue [][]int
res := 0
for i := 0; i < len(grid); i++ {
for j := 0; j < len(grid[i]); j++ {
if grid[i][j] == '1' {
queue = append(queue, []int{i, j})
for len(queue) > 0 {
row, col := queue[0][0], queue[0][1]
queue = queue[1:]
if row > 0 && grid[row-1][col] == '1' {
queue = append(queue, []int{row - 1, col})
grid[row-1][col] = '0'
}
if row < len(grid)-1 && grid[row+1][col] == '1' {
queue = append(queue, []int{row + 1, col})
grid[row+1][col] = '0'
}
if col > 0 && grid[row][col-1] == '1' {
queue = append(queue, []int{row, col - 1})
grid[row][col-1] = '0'
}
if col < len(grid[i])-1 && grid[row][col+1] == '1' {
queue = append(queue, []int{row, col + 1})
grid[row][col+1] = '0'
}
}
res++
}
}
}
return res
}
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