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lipm.go
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lipm.go
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package lipm
import (
"github.com/catorpilor/leetcode/utils"
)
func longestIncPath(matrix [][]int) int {
return dfsWithMemo(matrix)
}
// dfs got TLE
// dfsWithMemo time complexity is O(MN), space complexity O(MN)
func dfsWithMemo(matrix [][]int) int {
var res int
m := len(matrix)
if m < 1 {
return res
}
n := len(matrix[0])
if n < 1 {
return res
}
dirs := [5]int{-1, 0, 1, 0, -1}
memo := make([]int, m*n)
// visited := make([]bool, m*n)
for i := 0; i < m; i++ {
for j := 0; j < n; j++ {
out := helper(matrix, memo, dirs, i, j, m, n)
if out > res {
res = out
}
}
}
return res
}
func helper(matrix [][]int, memo []int, dirs [5]int, x, y, m, n int) int {
res := 1
// fmt.Printf("cur:(%d, %d)\n", x, y)
pos := x*n + y
if memo[pos] != 0 {
return memo[pos]
}
for i := 0; i < 4; i++ {
nx, ny := x+dirs[i], y+dirs[i+1]
if nx < 0 || nx >= m || ny < 0 || ny >= n || matrix[nx][ny] >= matrix[x][y] {
continue
}
res = utils.Max(res, 1+helper(matrix, memo, dirs, nx, ny, m, n))
// fmt.Printf("prev:(%d,%d), cur:(%d, %d), res:%d\n", x, y, nx, ny, res)
}
memo[pos] = res
return res
}