题目:
题解:
Go
var (
dirs = [][]int{[]int{-1, 0}, []int{1, 0}, []int{0, -1}, []int{0, 1}}
rows, columns int
)
func longestIncreasingPath(matrix [][]int) int {
if len(matrix) == 0 || len(matrix[0]) == 0 {
return 0
}
rows, columns = len(matrix), len(matrix[0])
outdegrees := make([][]int, rows)
for i := 0; i < rows; i++ {
outdegrees[i] = make([]int, columns)
}
for i := 0; i < rows; i++ {
for j := 0; j < columns; j++ {
for _, dir := range dirs {
newRow, newColumn := i + dir[0], j + dir[1]
if newRow >= 0 && newRow < rows && newColumn >= 0 && newColumn < columns && matrix[newRow][newColumn] > matrix[i][j] {
outdegrees[i][j]++
}
}
}
}
queue := [][]int{}
for i := 0; i < rows; i++ {
for j := 0; j < columns; j++ {
if outdegrees[i][j] == 0 {
queue = append(queue, []int{i, j})
}
}
}
ans := 0
for len(queue) != 0 {
ans++
size := len(queue)
for i := 0; i < size; i++ {
cell := queue[0]
queue = queue[1:]
row, column := cell[0], cell[1]
for _, dir := range dirs {
newRow, newColumn := row + dir[0], column + dir[1]
if newRow >= 0 && newRow < rows && newColumn >= 0 && newColumn < columns && matrix[newRow][newColumn] < matrix[row][column] {
outdegrees[newRow][newColumn]--
if outdegrees[newRow][newColumn] == 0 {
queue = append(queue, []int{newRow, newColumn})
}
}
}
}
}
return ans
}